BMW Coupes and Sedans 1970-1988 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



1600, 2000 and 2002 Models

See Figures 1 and 2

To prevent warpage of the aluminum head, the engine must be cold. This means a coolant temperature of less than 96°F (36°C).

  1. Remove the air cleaner and disconnect the breather tube. On fuel injected engines, remove the intake manifold as detailed earlier.
  2.  
  3. Disconnect the negative battery cable and drain the cooling system.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: An example of a 4-cylinder engine cylinder head and associated parts



Click image to see an enlarged view

Fig. Fig. 2: Cylinder head torque sequence-1600, 2000 and 2002models


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the choke cable, if equipped.
  2.  
  3. Disconnect the throttle linkage. On automatic transmission equipped models, disconnect the downshift linkage. On models equipped with the Solex 32 DIDTA type carburetor, disconnect and mark all electrical leads.
  4.  
  5. On 2002Tii models, disconnect the throttle butterfly linkage, and all electrical leads, marking each lead as it is being removed. Pull the torsion shaft towards the firewall until the ball is free of the torsion shaft.
  6.  
  7. Remove and tag the vacuum hoses. On models equipped with the emission control air pump, disconnect the vacuum hose with the non-return valve from its fitting on the intake manifold.
  8.  
  9. Disconnect the coolant hoses from the cylinder head. Disconnect intake manifold water hoses, if so equipped.
  10.  
  11. Tag and disconnect the electrical wiring and connectors from the cylinder head and engine components.
  12.  
  13. On carbureted models, disconnect and plug the fuel line on the tank side of the fuel pump.
  14.  
  15. On 1975 models, disconnect and plug the fuel and reflow hose.
  16.  
  17. On the fuel injected models, disconnect the fuel line at the injection pump and all lines at the injectors.
  18.  
  19. Remove the cylinder head cover and the front upper timing case cover.
  20.  
  21. Rotate the engine until the distributor rotor points to the notch on the distributor body edge and the timing indicator points to the second notch on the pulley
  22.  
  23. On 2002 models. No. 1 piston should now be at TDC on its firing stroke.
  24.  
  25. Remove the timing chain tensioner piston by removing the plug in the side of the block.
  26.  


CAUTION
The plug is under heavy spring tension.

  1. Open the lockplates, remove the retaining bolts and remove the timing chain sprocket from the camshaft.
  2.  

The dowel pin hole on the camshaft flange should be in the 6 o'clock position while the notch at the top for the cam flange should be aligned with the cast projection on the cylinder head and in the 12 o'clock position for proper installation.

  1. Remove the exhaust pipe from the exhaust manifold.
  2.  
  3. Remove the dipstick holder.
  4.  
  5. Unscrew the cylinder head bolts in the reverse of the tightening sequence and remove the cylinder head.
  6.  

To install:
  1. Clean the new head bolts and the bores of the cylinder block. Do not allow oil or contaminants to fill the bores. Use a 0.012 inch (0.3mm) thicker gasket if the head was machined. Install a new gasket for the timing case at the front of the cylinder head.
  2.  
  3. Install a new head gasket in the proper orientation as marked on the gasket. Check the condition of the guide dowels in the cylinder deck.
  4.  
  5. Tighten the new head bolts in a crisscross pattern starting at the center of the head and working towards the ends. Tighten to 24 ft. lbs. (33 Nm), then turn 93 degrees, then finish with a final turn of 93 degrees.
  6.  
  7. Install the timing chain, timing guide bolt on the right side and the upper chain guide.
  8.  
  9. If not installing a new tensioner piston, knock the outer sleeve of the tensioner piston so the piston is released from the sleeve. Assemble the tensioner with the spring, the piston and the snaprings in position. Place in a vice and press together until both snaprings engage. If the piston starts to extend, the procedure must be done again. The compressed tensioner will be 2.7 inches (68.5mm).
  10.  
  11. Install the tensioner into its bore and tighten the plug to 17-19 ft. lbs. (23-27 Nm). Push the tensioner rail against the tensioner to release the tensioner piston.
  12.  
  13. Install the front timing upper cover with new gaskets and fill the gaps with non hardening sealer. Press down on the cover to align it with the cylinder head. Install the bolts and tighten to 6-7 ft. lbs. (8-10 Nm) for grade M6 bolts and 15-17 ft. lbs. (20-22 Nm) for grade M8 bolts.
  14.  
  15. Install the remaining components in the reverse order of removal.
  16.  

2500, 2800, 3000, Bavaria, 3.0 and 630i Models

See Figure 3

  1. Disconnect the battery ground cable. Drain the cooling system.
  2.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect throttle linkage rods running between the carburetors.
  2.  
  3. Disconnect the water temperature sensor at the thermostat and the electrically heated choke wires.
  4.  
  5. Remove the power brake hose from the base of the front carburetor. Remove the dipstick support.
  6.  
  7. Disconnect the heater and water hoses to the intake manifold.
  8.  
  9. Disconnect and remove the air cleaner assembly and hoses.
  10.  
  11. Remove the ignition high tension wire tube.
  12.  
  13. Disconnect the inductive switch and cable off the coil. Remove the distributor cap and disconnect the primary wire and vacuum line from the distributor.
  14.  
  15. Disconnect the 2 vacuum hoses at the rear of the intake manifold, and the 2 fuel lines at the fuel manifold.
  16.  
  17. Disconnect the water hoses for the heater at the firewall and disconnect the equalizing reservoir hose at the reservoir. Disconnect the oil pressure switch line at the plug.
  18.  
  19. Disconnect and remove the air volume control assembly. Disconnect the ignition cable tube and wires and remove it, and disconnect the cam cover vent hose.
    1. Mark locations and then disconnect the 3 coil connections.
    2.  
    3. Disconnect all 6 injection valve plugs, and the plug at the throttle switch. Disconnect the throttle linkage rod at the top and bottom.
    4.  
    5. Disconnect the vacuum hose from the throttle housing and disconnect the temperature sensor wire at the front of the head.
    6.  
    7. Disconnect the water hose at the throttle housing and the oil pressure switch wire.
    8.  
    9. Disconnect water hoses at the thermostat housing. Disconnect the hose going to the charcoal filter. Disconnect the fuel feed line at the filter.
    10.  
    11. On 630i models only, remove the connector from between No. 2 and 3 cylinder intake tubes.
    12.  
    13. Disconnect the 4 vacuum sensing hoses from the EGR valve and collector/vacuum valve, noting color coding and locations. Disconnect the brake booster vacuum hoses at the manifold.
    14.  
    15. Disconnect heater hoses at the firewall, noting locations. Disconnect the 2 air hoses at the auxiliary air valve; disconnect the 2 electrical connectors at the auxiliary air valve. Then, remove the auxiliary air valve wiring harness through the opening in the intake manifold.
    16.  
    17. Disconnect and remove the EGR filter.
    18.  

  20.  
  21. Remove the cylinder head cover.
  22.  
  23. Rotate the engine so that the distributor rotor points to the notch on the distributor body edge and the timing indicator points to the notch on the belt pulley. This will place number one piston at TDC on its firing stroke.
  24.  
  25. Remove the upper timing housing cover after removing the distributor and thermostat housing.
  26.  
  27. Remove the timing chain tensioner piston.
  28.  
  29. Open the camshaft sprocket bolt lockplates and remove the bolts. Remove the sprocket.
  30.  

For installation purposes, the sprocket dowel pin should be located at the lower left, between 7 and 8 o'clock, while the upper bolt bore must align with the threaded bore of the camshaft and the cylinder head cast tab, visible through the 2 bores, when at the 12 o'clock position.

  1. Disconnect the exhaust system at the exhaust manifold. Remove the exhaust filter, if equipped.
  2.  
  3. Remove the cylinder head bolts in the reverse order of the tightening sequence and install locating pins in 4 head bolt bores to prevent the rocker shafts from turning.
  4.  
  5. Remove the cylinder head.
  6.  

To install:
  1. Apply a very light coating of oil to the head bolts. Don't let oil get into the bolt holes or apply excessive amounts of oil, or torque specifications could be incorrect and the block could crack.
  2.  
  3. Tighten bolts 1-6 in the correct torque order to 42-44 ft. lbs. (57-60 Nm). Remove the pins holding the rocker shafts in place. Now, complete the first stage of torquing by tightening bolts 7-14 in the correct order, to the same specification.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Cylinder head torque sequence-2500, 2800, 3000, Bavaria and 630i models

  1. Wait 20 minutes. Then tighten to 57-59 ft. lbs. (78-82 Nm).
  2.  
  3. Once the procedure is completed, run the engine for 25 minutes. Tighten the bolts, in the correct order, with a torque angle gauge 30-40 degrees.
  4.  
  5. Reinstall the timing sprocket to the camshaft. Make sure the camshaft is in proper time, and that new lock plates are used, and that nuts are properly tighten.
  6.  
  7. Install the tensioner piston.
  8.  
  9. When reinstalling the timing cover, make sure to apply a liquid sealer to the joints between the upper and lower timing covers.
  10.  
  11. The remainder of installation is the reverse of removal. Note these points:
    1. Adjust throttle, speed control, and accelerator cables.
    2.  
    3. Inspect and if necessary replace the exhaust manifold gasket.
    4.  
    5. When reinstalling the cylinder block coolant plug, coat it with sealer.
    6.  
    7. Install the timing chain so the down pin on the camshaft sprocket is at the 8 o'clock position when its tapered bores are at right angles to the engine. Tighten the sprocket bolts to 6.5-7.5 ft. lbs. (8-10 Nm).
    8.  
    9. Check the camshaft cover gasket, replacing, as necessary. Tighten camshaft cover bolts in the order shown. Tighten the bolts to 6.5-7.5 ft. lbs. (8-10 Nm).
    10.  
    11. Make sure to refill the cooling system and bleed it.
    12.  
    13. Make sure to refill the oil pan with the correct amount of oil.
    14.  

  12.  

318i and 320i Models

See Figure 4

  1. Disconnect the exhaust pipes at the exhaust manifold and remove the pipe clamp on the transmission.
  2.  
  3. Disconnect the negative battery cable. Remove the drain plug and drain coolant.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect the wires and plug on the air cleaner. Loosen the clamp and disconnect the air intake hose. Then unscrew the nuts and remove the air cleaner.
  2.  
  3. Disconnect the throttle cable. Remove the dipstick tube locating bracket.
  4.  
  5. Disconnect the throttle position electronic plug. Disconnect the coolant and vacuum hoses nearby. Unscrew the support for the throttle body nearby.
  6.  
  7. Detach the fuel supply and return hoses as well as the hose mounting clamp.
  8.  
  9. Disconnect the intake manifold, distributor, and power brake unit vacuum hoses.
  10.  
  11. Disconnect the diagnosis plug, alternator wiring, and other plugs (2) nearby. Disconnect the coolant hoses at the cylinder head.
  12.  
  13. Disconnect any electrical plugs on the starter and injection system. This includes pulling off each injection plug and opening up the wiring straps.
  14.  
  15. Remove the distributor cap, wiring harness, and all plug wires.
  16.  
  17. Disconnect the coolant hoses going into the firewall.
  18.  
  19. Remove the cylinder head cover. Remove the bracket near the upper timing case over. Then, remove the bolts and remove the upper timing case cover.
  20.  
  21. Rotate the engine until the TDC mark on the front pulley is aligned with the mark on the front cover and the distributor rotor is aligned with the mark on the side of the distributor (No. 1 cylinder is at TDC). Then, remove the distributor.
  22.  
  23. Remove the timing chain tensioner piston as described in this section.
  24.  
  25. Remove the retaining bolts and pull off the upper timing chain sprocket.
  26.  

Do not rotate the crankshaft while the sprocket is off.

  1. Loosen the cylinder head bolts in reverse order of the torquing sequence and remove. Lift off the cylinder head.
  2.  

To install:
  1. Install in reverse order, noting these points:
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Cylinder head torque sequence-318i and 320i models

    1. Use a new head gasket. Install the head gasket in the proper orientation as marked on the gasket. Check the condition of the guide dowels in the cylinder deck.
    2.  
    3. Lightly oil all head bolts, keeping oil out of the threaded holes in the block.
    4.  
    5. Tighten in the sequence shown in 3 stages. Tighten the new head bolts in a crisscross pattern starting at the center of the head and working towards the ends. Tighten to 24 ft. lbs. (33 Nm), then turn 93 degrees, then finish with a final turn of 93 degrees.
    6.  


  1. Install the timing chain, timing guide bolt on the right side and the upper chain guide.
  2.  
  3. Assemble the tensioner with the spring, piston and the snaprings in position. Place in a vice and press together until both snaprings engage. If the piston starts to extend, the procedure must be done again. The compressed tensioner will be 2.7 inches (68.5mm).
  4.  
  5. Install the tensioner into its bore and tighten the plug to 17-19 ft. lbs. (23-27 Nm). Push the tensioner rail against the tensioner to release the tensioner piston.
  6.  
  7. Install the front timing upper cover with new gaskets and fill the gaps with non hardening sealer. Press down on the cover to align it with the cylinder head. Install the bolts and tighten to 6-7 ft. lbs. (8-10 Nm) for grade M6 bolts and 15-17 ft. lbs. (20-22 Nm) for grade M8 bolts.
  8.  
  9. Install the remaining components in the reverse order of removal.
  10.  

1982-87 325, 325e, 325i, 325iS, 325iX and 528e Models

See Figures 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the exhaust pipes at the manifold and at the transmission clamp.
  4.  
  5. Remove the drain plug at the bottom of the radiator and drain the coolant.
  6.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect the accelerator and cruise control cables. If the vehicle has automatic transmission, disconnect the throttle cable that goes to the transmission.
  2.  
  3. Working at the front of the block, disconnect the upper radiator hose, the bypass water hose, and smaller water hoses. Remove the diagnosis plug located at the front corner of the manifold. Remove the bracket located just underneath. Disconnect the fuel line and drain the contents into a metal container for safe disposal.
  4.  



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Fig. Fig. 5: Remove the accelerator cable and bracket-3 Series



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Fig. Fig. 6: Disconnect the vacuum hoses attached to the intake manifold including the cold start valve hose. Tag each hose after removing



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Fig. Fig. 7: Unfasten the clip securing the diagnostic harness attached to the intake manifold



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Fig. Fig. 8: Remove the bracket for the diagnostic harness



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Fig. Fig. 9: Detach the dipstick tube bracket

  1. Working on the air cleaner/airflow sensor, disconnect the vacuum hoses, labeling them if necessary. Unfasten all electrical connectors and unclip and remove the wiring harness. There is a relay located in an L-shaped box near the strut tower. Disconnect and remove it. Unclamp and remove the air hose. Remove the mounting nuts and remove the assembly.
  2.  
  3. Disconnect the hose at the coolant overflow tank. Disconnect the idle speed positioner vacuum hose and then remove the positioner from the manifold.
  4.  
  5. If equipped with 4-wheel drive, disconnect the vacuum hose from the servo mounted on the manifold.
  6.  
  7. Place a drain pan underneath and then unfasten the water connections at the front of the intake manifold. Unfasten the electrical connector.
  8.  
  9. Unbolt the dipstick tube bracket at the manifold. Remove the fuel hose bracket at the cylinder head. Make sure the engine is cold. Then, place a metal container under the connection and unfasten the fuel hose at the connection.
  10.  
  11. Unfasten the fuel injector connectors at all 6 injectors, as well as the 2 additional electrical connectors to the sensors on the head.
  12.  
  13. Unfasten the oil pressure sending unit connector. Then, unfasten the carriers and remove this wiring.
  14.  
  15. Unfasten the coil high tension wire and unfasten the high tension wires at the spark plugs. Then, disconnect the tube in which the wires run above the valve cover. Disconnect the PCV hose. Then, remove the retaining nuts and remove the valve cover.
  16.  
  17. Turn the crankshaft so the TDC line is aligned with the indicator and the valves of No. 6 cylinder are overlapping in the slightly open position.
  18.  



Click image to see an enlarged view

Fig. Fig. 10: Remove the fuel supply rail bolts. Be careful not to drop any of the bolts after removing them



Click image to see an enlarged view

Fig. Fig. 11: Slide the rail out from under the intake manifold



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Fig. Fig. 12: Remove the protective cover over the distributor cap, then remove the distributor cap



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Fig. Fig. 13: With the distributor cap removed, unfasten the bolts securing the upper timing belt cover



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Fig. Fig. 14: Remove the upper timing belt cover



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Fig. Fig. 15: The lower timing belt cover can also be removed for more access



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Fig. Fig. 16: Paint alignment marks on the timing belt and pulleys



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Fig. Fig. 17: Loosen the timing belt tensioner



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Fig. Fig. 18: Slide the timing belt off without moving the pulleys



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Fig. Fig. 19: Cylinder head torque sequence-3 Series and 528e models

  1. Remove the distributor cap. Then, unscrew and remove the rotor. Unscrew and remove the adapter just underneath the rotor. Remove the cover underneath the adapter. Check its O-ring and replace it, if necessary.
  2.  
  3. Remove the distributor mounting bolts and the protective cover.
  4.  
  5. These engines are equipped with a rubber timing belt. Remove the belt covers. To loosen the belt tension, loosen the tension roller bracket pivot bolt and adjusting slot bolt. Push the roller and bracket away from the belt to release the tension, hold the bracket in this position, and tighten the adjusting slot bolt to retain the bracket it this position.
  6.  
  7. Remove the timing belt.
  8.  

Make sure to avoid rotating both the engine and camshaft from this point onward.

  1. Remove the cylinder head mounting bolts in exact reverse order of the proper tightening sequence. Then, remove the cylinder head.
  2.  

To install:
  1. Clean both cylinder head and block sealing surfaces thoroughly with a hardwood scraper. Inspect the surfaces for flatness.
  2.  
  3. Install the head with a new gasket. Check that all passages line up with the gasket holes. Clean the threads on the head bolts and coat with a light coating of oil. Keep oil out of the bolt cavities in the head or the head could be cracked or proper tightening affected.
  4.  
  5. Tighten the bolts in a crisscross pattern staring at the center of the head and working towards the end. If equipped with hex head bolts, tighten to 29-34 ft. lbs. (40-45 Nm). Wait 15 minutes, then tighten to 43-47 ft. lbs. (60-65 Nm). After the installation is completed, run the engine for 25 minutes and give the bolts a final turn of 25-30 degrees. If equipped with Torx bolts, tighten to 22 ft. lbs. (30 Nm), turn 90 degrees, then complete with an additional 90 degrees. Do not wait or run engine.
  6.  
  7. Adjust the valves.
  8.  
  9. Complete the installation by reversing the removal procedures.
  10.  
  11. Replace the gaskets for the exhaust system connections, if necessary. Coat the studs with the proper sealant. Note that the plugs for the DME reference mark and speed signals should be connected so the gray plug goes to the socket with a ring underneath.
  12.  

Align the timing marks when installing the timing belt. The crankshaft sprocket mark must point at the notch in the flange of the front engine cover. The camshaft sprocket arrow must point at the alignment mark on the cylinder head. Also, the No. 1 piston must be at TDC of the compression stroke. BMW recommends that the timing belt be replaced every time the cylinder head is removed and the belt is disturbed as a consequence. Tension the belt. when complete.

  1. Make sure to refill the engine oil pan and cooling system with proper fluids and to bleed the cooling system.
  2.  

1988 325, 325e, 325i, 325iS, 325iX and 528e Models

See Figure 19

  1. Unbolt the exhaust pipe connections at the manifold and at the transmission pipe clamp.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the splash shield from under the engine.
  6.  
  7. Remove the drain plugs from the bottom of the radiator and engine block.
  8.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Drain the engine oil.
  2.  
  3. Disconnect the throttle and cruise control cables at the throttle lever. Unbolt the cable housing retainer and remove the housing and cables.
  4.  
  5. Loosen the hose clamp and disconnect the air inlet hose from the airflow sensor.
  6.  
  7. The unit on the opposite side of the intake hose from the air cleaner contains the idle speed control valve, which must be removed next. Loosen the hose clamps and pull off the hoses. Unfasten the electrical connector. Remove the mounting nut and then pull the idle speed control out of the air intake hose.
  8.  
  9. Disconnect and plug the brake booster vacuum line.
  10.  
  11. Unfasten the radiator hoses, the heater hoses and the fuel lines. Mark the lines for ease of installation.
  12.  
  13. Unfasten the venting valve vacuum line and electrical connector from under the intake manifold. Unfasten the connections on the plug plate located under the intake manifold and remove the plug plate.
  14.  
  15. Remove the fan. Lift out the expansion rivets on either side and remove the fan shroud.
  16.  
  17. Disconnect the throttle body coolant hoses. Loosen the mount for the engine oil dipstick.
  18.  
  19. Disconnect the plugs near the thermostat housing. Loosen the hose clamps and pull off the coolant hoses.
  20.  
  21. Disconnect the plug in the line leading to the oxygen sensor. Disconnect the other plugs.
  22.  
  23. Disconnect the fuel supply and return lines, collecting fuel in a metal container for safe disposal.
  24.  
  25. Unfasten the fuel pipe running along the cylinder head, near the manifold. Pull off the electrical connector at the throttle body. Remove the caps, then remove the attaching bolts and remove the wiring harness carrier and harness for the fuel injectors.
  26.  
  27. Disconnect the coil high tension lead. Disconnect the high tension wires at the plugs. Then, remove the mounting nuts and remove the carrier for the high tension wires from the head.
  28.  
  29. Remove the timing belt. The timing belt must be replaced anytime it is removed or the tensioner loosened.
  30.  
  31. Remove the heater hose from the cylinder head. Press down on the venting pipe collar and lock into position. Remove the valve cover. Check for any remaining connections that may have been missed.
  32.  
  33. Remove the head bolts in a crisscross pattern starting at the center and working out toward the ends. Lift off the head.
  34.  

To install:
  1. Make checks of the lower cylinder head and block deck surface to make sure they are true. Install a new head gasket, making sure all bolt, oil, and coolant holes line up. Use a 0.3mm thicker gasket, if the head has been machined.
  2.  
  3. Apply a very light coating of oil to the head bolts. Don't let oil get into the bolt holes or apply excessive amounts of oil, or tightening amounts could be incorrect and the block could crack.
  4.  
  5. Use the type of bolt without a collar. Install the bolts, finger tight.
  6.  
  7. Tighten the bolts in a crisscross pattern staring at the center of the head and working towards the end. If equipped with hex head bolts, tighten to 29-34 ft. lbs. (40-45 Nm). Wait 15 minutes then tighten to 43-47 ft. lbs. (60-65 Nm). After the installation is completed, run the engine for 25 minutes and give the bolts a final turn of 25-30 degrees.
  8.  

If equipped with Torx® bolts, tighten to 22 ft. lbs. (30 Nm), turn 90 degrees, then complete with an additional 90 degrees.

  1. Adjust the valves.
  2.  
  3. Connect the venting pipe and release the collar. Connect the heater hose on the cylinder head.
  4.  
  5. Connect the throttle body coolant hoses and install the wiring harnesses and injector plugs.
  6.  
  7. Connect the sensors and vacuum lines.
  8.  
  9. Install a new timing belt. Never reuse a timing belt.
  10.  
  11. Install the fan and cowl.
  12.  
  13. Connect the fuel lines, air intake hoses, vacuum lines, idle air control and throttle cables.
  14.  
  15. Fill the engine with fluids and bleed the coolant system. Connect the exhaust system and the negative battery terminal.
  16.  

524td Models

See Figures 20 and 21

To perform this procedure, a number of special tools will be needed. These include a dial indicator with a bridge that will allow the gauge to measure piston protrusion while the edges of the bridge rest on the block deck on either side of the piston; and an angle gauge for measuring turning angle of cylinder head bolts; some means of holding the camshaft in position, such as BMW tool 11 3 090.

  1. Disconnect the battery ground cable.
  2.  
  3. Remove the turbocharger as described in this section.
  4.  
  5. Remove the fan. Remove the drain plug from the radiator and drain the cooling system. Then, remove the coolant hoses connected to the water pump.
  6.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect the coolant hose located at the front of the intake manifold. Unfasten the electrical plug near this hose connection. Unfasten the injector leak-off line that also connects near these connections.
  2.  
  3. Unfasten the heater hose nearby and under the intake manifold. Remove the bracket next to this hose connection and then disconnect the glow plug wiring.
  4.  
  5. Working inside the glove compartment, unfasten the multi-prong plug on the electronic control unit. Then, unfasten the engine wiring harness at the 2 fasteners on the firewall and pull the harness into the engine compartment.
  6.  
  7. Disconnect the crankcase ventilation hose at the rear of the valve cover. Then, unfasten the 3 electrical plugs right nearby. Disconnect the diagnostic (multi-prong) plug.
  8.  
  9. Disconnect the small coolant hose located to the right of the intake air box. Then, unfasten any remaining flow plug wires nearby. Unfasten the temperature sensor connectors nearby. Then, disconnect the plug at the firewall.
  10.  
  11. Remove the intake air box bracket located near the rear of the intake air box. Then, unfasten the wiring harness from the retaining clips and move it downward and out of the way.
  12.  
  13. Disconnect the transmission dipstick tube bracket at the intake manifold. Disconnect the air hose at the manifold, nearby. Unfasten the wire at the intake pressure relief valve, nearby.
  14.  
  15. Remove the crankcase ventilation system oil trap from the valve cover by first unfastening the hose and then unbolting it and removing it with its gasket.
  16.  
  17. Use a crowfoot wrench or equivalent tool to unscrew and remove the injection lines at the pump and injectors. Plug all the openings with clean, protective caps.
  18.  
  19. Remove the cam cover. Then, turn the engine until No. 1 cylinder is at TDC (No. 6 cylinder's valves overlap). Either lock the crank in position with a pin such as BMW special tool 11 2 300 or equivalent, or make sure the crankshaft is completely undisturbed until the engine is reassembled.
  20.  
  21. Remove the coolant hose which runs across the front of the timing belt cover and remove the timing belt cover. Then, loosen the camshaft sprocket retaining bolt. Loosen the bolt and nut which position the timing belt tensioner and then remove the timing belt.
  22.  
  23. Remove the cylinder head bolts in the order of 14-1, going in rotation in several stages. Lift the head off the engine.
  24.  



Click image to see an enlarged view

Fig. Fig. 20: Check the height above the block deck of each piston at location A and B



Click image to see an enlarged view

Fig. Fig. 21: Cylinder head torque sequence-524td models

To install:
  1. Clean the block deck and cylinder head lower surfaces with a solvent and wooden scraper (to avoid scoring either surface).
  2.  
  3. Set up and zero a dial indicator which will allow you to measure the protrusion of the pistons above the block deck. Measure the protrusion of each piston along the center-line of the block on the flat surface at both the front and rear of the piston. Rock the engine back and forth for each cylinder until absolute maximum protrusion is obtained. Average the 2 readings for each piston and record. Return the crankshaft to No. 6 cylinder overlap position. Note the highest protrusion. Compare it to these figures and select a head gasket of the appropriate thickness from the protrusion figure:

    0.025-0.030mm 1 hole
     
    0.031-0.035mm 2 holes
     
    0.036-0.042mm 3 holes
     

  4.  

Gaskets have one, 2, or 3 holes along one edge to indicate the thickness classification.

  1. Clean all the cylinder head bolts with solvent and give them a very light coating of engine oil. Make sure the bolts are not heavily coated with oil and that the bolt holes do not contain any oil, as this will interfere with the tightening rate and might even crack the cylinder block.
  2.  
  3. Turn the camshaft so that the valves on cylinder No. 6 are at the overlap position. Make sure the camshaft does not turn from this position, or the valves may be bent when the head is installed. Use a jig such as BMW tool 11 3 090 or equivalent. Install the bolts and then tighten them in the numbered order, starting from the center and working out. Tighten each bolt to 50-60 ft. lbs. (65-78 Nm). Wait 15 minutes then retighten to 70-76 ft. lbs. (91-99 Nm).
  4.  
  5. Install and adjust the timing belt as described in this section. Adjust the valves and install the cam cover. Then, install the timing belt cover.
  6.  
  7. Install the injection pump lines and tighten the fittings to 14-18 ft. lbs. (18-23 Nm).
  8.  
  9. Bleed the fuel system.
  10.  
  11. Reconnect all electrical lines, hoses, and other fittings so the engine is ready to run.
  12.  
  13. Use a new gasket on the crankcase ventilation system oil trap. Refill the cooling system.
  14.  
  15. Start the engine and run it at about 1000 rpm until it is hot. Then, remove the valve cover, and again in numerical order, final-tighten the bolts by accurately turning them another 90° tighter. Use a tool designed for angle torquing such as BMW 11 2 110.
  16.  
  17. Replace the valve cover.
  18.  

530i, 533i, 633CSi and 733i Models

See Figure 22

  1. Unbolt the exhaust pipes at the exhaust manifold. Unclamp the exhaust pipe at the transmission.
  2.  
  3. Disconnect the battery negative then positive cables.
  4.  
  5. Drain the coolant by removing the plugs from the radiator and engine block.
  6.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Disconnect the throttle, accelerator, and cruise control cables at the throttle body.
  2.  
  3. These engines are all virtually identical, but wiring harnesses vary from model to model. Systematically unfasten all wiring that goes to the cylinder head, or would obstruct head removal. This includes wiring to the airflow sensor, ignition wiring and, wires to the fuel injectors, and on some models it may be necessary to unfasten the alternator wiring.
  4.  
  5. Disconnect the fuel lines, vacuum lines, and heater and coolant hoses that are in the way. Unfasten the DME plugs on models so equipped. Note that the gray plug connects to the sleeve with a ring underneath, for proper installation.
  6.  
  7. Remove the air cleaner and the windshield washer tank.
  8.  
  9. Remove the valve cover.
  10.  
  11. Disconnect the ground lead. Then, complete unfastening the engine wiring harness by disconnecting the oil pressure sending unit and set the harness aside.
  12.  
  13. Remove the upper timing case cover, tensioner piston, and then open the lockplates and remove the timing chain upper sprocket. Make sure to suspend the sprocket so the timing chain position isn't lost.
  14.  
  15. Loosen the cylinder head bolts following the illustration in reverse order. Install 4 special pins BMW part No. 11 1 063 or equivalent. This is necessary to keep the rocker arm shafts from moving. Then, lift off the head.
  16.  

To install:
  1. Make checks of the lower cylinder head and block deck surface to make sure they are true.
  2.  
  3. Install a new head gasket, making sure that all bolt, oil, and coolant holes line up. Use a 0.3mm thicker gasket if the head has been machined.
  4.  



Click image to see an enlarged view

Fig. Fig. 22: Cylinder head torque sequence-530i, 533i, 633CSi and 733i models

  1. Apply a very light coating of oil to the head bolts. Don't let oil get into the bolt holes or the tighten rate could be incorrect and the block could crack. Use the newer type of bolt without a collar. Install the bolts, finger-tight.
  2.  
  3. Tighten bolts 1-6 in the order to 42-44 ft. lbs. (57-60 Nm). Remove the pins holding the rocker shafts in place. Now, complete the first stage of tightening by torquing bolts 7-14 in the correct order, to the same specification.
  4.  
  5. Wait 20 minutes. Tighten the bolts to 57-59 ft. lbs. (78-82 Nm). Once the procedure is completed, run the engine for 25 minutes. Tighten the bolts, in the correct order, with a torque angle gauge 30-40 degrees.
  6.  
  7. Reinstall the timing sprocket to the camshaft. Make sure the cam is in proper time, that new lockplates are used, and that nuts are properly tightened.
  8.  
  9. When reinstalling the timing cover, make sure to apply a liquid sealer to the joints between upper and lower timing covers. The remainder of installation is the reverse of removal. Note these points.
    1. Adjust throttle, speed control, and accelerator cables. Inspect and if necessary replace the exhaust manifold gasket.
    2.  
    3. When reinstalling the cylinder block coolant plug, coat it with sealer. Make sure to refill the cooling system and bleed it (see the Cooling System procedure below).
    4.  

  10.  

535i, 635CSi and 735i Models

See Figure 23

  1. Unbolt the exhaust pipe connections at the manifold and at the transmission pipe clamp. Disconnect the negative battery cable.
  2.  
  3. Remove the splash shield from under the engine. With the engine cool, remove the drain plugs from the bottom of the radiator and block.
  4.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Drain the engine oil.
  2.  


CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

  1. Remove the fan. Lift out the expansion rivets on either side and remove the fan shroud.
  2.  
  3. Loosen the hose clamp and unfasten the air inlet hose. Remove the mounting nut and remove the air cleaner.
  4.  
  5. The unit on the opposite side of the intake hose from the air cleaner contains the idle speed control valve, which must be removed next. Loosen the hose clamps and pull off the hoses. Unfasten the electrical connector. Remove the mounting nut and then pull the idle speed control unit out of the air intake hose.
  6.  
  7. Pull off the 3 retainers for the airflow sensor, and then pull the unit off its mounting, disconnecting the vacuum hose from the PCV system at the same time.
  8.  
  9. Working on the coolant expansion tank, unfasten the electrical connector. Remove the nuts on both sides. Loosen their clamps and then disconnect all 3 hoses and remove the tank.
  10.  
  11. Unfasten the heater hoses at both the control valve and at the heater core.
  12.  
  13. Disconnect the throttle and cruise control cables at the throttle lever. Unbolt the cable housing retainer and remove the housing and cables.
  14.  
  15. Disconnect the 4 plugs near the thermostat housing. Loosen the hose clamps and pull off the 2 coolant hoses.
  16.  



Click image to see an enlarged view

Fig. Fig. 23: Cylinder head torque sequence-535i, 635i and 735i models

  1. Disconnect the plug in the line leading to the oxygen sensor. Unfasten the other 2 plugs nearby.
  2.  
  3. Disconnect the fuel supply and return lines, collecting fuel in a metal container for safe disposal.
  4.  
  5. Disconnect the fuel pipe running along the cylinder head, near the manifold. Pull off the electrical connector at the throttle body. Remove the caps, then remove the attaching bolts and remove the wiring harness carrier and harness for the fuel injectors.
  6.  
  7. Unfasten the coil high tension lead. Disconnect the high tension wires at the plugs. Then, remove the mounting nuts and remove the carrier for the high tension wires from the head.
  8.  
  9. Remove the attaching nuts for the valve cover and remove it.
  10.  
  11. Turn the engine until the timing marks are at TDC and the No. 6 valves are at overlap (both slightly open) position.
  12.  
  13. Remove the upper timing case cover. Remove the timing chain tensioner piston.
  14.  
  15. Remove the 4 upper timing chain sprocket bolts and pull the sprocket off, holding it upward and then support it securely so the relationship between the chain and sprocket top and bottom will not be lost.
  16.  
  17. Disconnect the upper radiator hose at the thermostat housing. Remove the 3 bolts and remove the support for the intake manifold.
  18.  
  19. Remove the cylinder head bolts in the opposite order of the torquing sequence. Then, install 4 special pins BMW part No. 11 1 063 or equivalent. This is necessary to keep the rocker arm shafts from moving. Then, lift off the head.
  20.  

To install:
  1. Make checks of the lower cylinder head and block deck surface to make sure they are true.
  2.  
  3. Install a new head gasket, making sure that all bolt, oil, and coolant holes line up. Use a 0.3mm thicker gasket if the head has been machined.
  4.  
  5. Apply a very light coating of oil to the head bolts. Don't let oil get into the bolt holes or the tightening rate could be incorrect and the block could crack. Use the newer type of bolt without a collar. Install the bolts, finger tight.
  6.  
  7. Tighten bolts 1-6 in the correct order to 42-44 ft. lbs. (57-60 Nm). Remove the pins holding the rocker shafts in place. Now, complete the first stage of tightening by torquing bolts 7-14 in the correct order, to the same specification.
  8.  
  9. Wait 20 minutes. Tighten the bolts to 57-59 ft. lbs. (78-82 Nm). Once the procedure is completed, run the engine for 25 minutes. Tighten the bolts, in the correct order, with a torque angle gauge 30-40 degrees.
  10.  
  11. Reinstall the timing sprocket to the camshaft. Make sure the cam is in proper time, and that new lockplates are used.
  12.  
  13. When reinstalling the timing cover, make sure to apply a liquid sealer to the joints between upper and lower timing covers. The remainder of installation is the reverse of removal. Note these points.
    1. Adjust throttle, speed control, and accelerator cables. Inspect and if necessary replace the exhaust manifold gasket.
    2.  
    3. When reinstalling the cylinder block coolant plug, coat it with sealer. Make sure to refill the cooling system and bleed it.
    4.  

  14.  

M3 Model

See Figure 24

This is an extremely difficult operation involving the use of a number of special tools. It is necessary to remove both of the camshafts to complete it. Refer to the camshaft removal and installation procedure below for information on those special tools required for that part of the job. It is also necessary to have a set of metric hex wrenches.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the splash guard from under the engine. Put drain pans underneath and remove the drain plugs from both the radiator and engine block to drain all coolant.
  4.  


CAUTION
When draining coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze, and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Loosen the hose clamps for the air intake hose located next to the radiator and then remove the hose.
  2.  
  3. Unfasten the electrical connectors for the airflow sensor. Then, remove the attaching nuts and remove the air cleaner/ airflow sensor assembly.
  4.  
  5. Disconnect the accelerator and cruise control cables, if equipped. Unbolt the cable mounting bracket and move the cables and bracket aside.
  6.  
  7. Remove the attaching nut, pull off the clamp, and then detach the vacuum hose from the brake booster.
  8.  



Click image to see an enlarged view

Fig. Fig. 24: Cylinder head torque sequence-M3 models

  1. Loosen the hose clamp and remove the air intake hose from the intake manifold. Remove the nut from the manifold brace.
  2.  
  3. Loosen the clamp and disconnect the other end of the booster vacuum hose at the manifold. Remove the nut from the intake manifold brace.
  4.  
  5. Loosen the hose clamp and disconnect the air intake hose at the manifold. Then, remove the nuts attaching the manifold assembly to the outer ends of the intake throttle necks and remove the assembly.
  6.  
  7. Put a drain pan underneath and loosen the hose clamps and disconnect the coolant expansion tank hoses. Disconnect the engine ground strap.
  8.  
  9. Unfasten the ignition coil high tension lead. Label and then disconnect the plugs on the front of the block.
  10.  
  11. All the fuel injectors are plugged into a common plate. Carefully and evenly pull the plate off the injectors, pull it out past the pressure regulator, and lay it aside.
  12.  
  13. Loosen the clamp and then disconnect the PCV hose. Label and then unfasten the fuel lines connecting with the injector circuit. Put a drain pan underneath and then unfasten the heater hose from the cylinder head.
  14.  
  15. Loosen the clamp near the throttle necks and then pull the engine wiring harness out and put it aside.
  16.  
  17. Put a drain pan underneath and then disconnect the heater hose that connects to the block.
  18.  
  19. Remove the bolts from the flanges connecting the exhaust pipes to the exhaust manifold. Provide new gaskets and self-locking nuts. Disconnect the oxygen sensor plug.
  20.  
  21. Put a drain pan underneath and then unfasten the radiator hoses from the pipe at the front of the block.
  22.  
  23. Pull off the spark plug connectors. Remove the nuts from the valve cover, located just to one side of the row of spark plugs. Remove the ignition lead tube. Remove the remaining nuts and remove the valve cover. Provide new gaskets.
  24.  
  25. It is not necessary to remove the timing chain completely, but it is necessary to remove the valve cover, front covers for the camshaft drive sprockets, the upper guide rail for the timing chain and then turn the engine to TDC firing position for cylinder No. 1. Remove the timing chain tensioner. Note the relationship between the chain and both the crankshaft and camshaft sprockets, and then remove both camshaft drive sprockets. Leave the chain in a position that will not interfere with removal of the head and which will minimize the alignment position.
  26.  
  27. Remove the camshafts.
  28.  
  29. Remove the camshaft followers one at a time, keeping them in exact order for installation in the same positions.
  30.  
  31. Remove the bolts that retain the timing case to the head at the front of the engine assembly.
  32.  
  33. Remove the coolant pipe that runs along the left/rear of the block. Remove one bolt at the left/front of the block that is located outside the valve cover. Then, go along in the area under the valve cover and remove all the remaining bolts for the timing case. Remove the timing case.
  34.  
  35. Remove the hex bolts fastening the head to the block at the front. These are located outside the valve cover and just behind the water pump drive belt. Then, remove the head bolts located under the valve cover in reverse order of the cylinder head tighten sequence.
  36.  

To install:

BMW does not recommend machining the head.

  1. Make checks of the lower cylinder head and block deck surface to make sure they are true. Clean both cylinder head and block sealing surfaces thoroughly. Lubricate the head bolts with a light coating of engine oil. Make sure there is no oil or dirt in the bolt holes in the block.
  2.  
  3. Install a new head gasket, making sure all bolt, oil, and coolant holes line up. Install the bolts as follows:
    1. Tighten them in the correct order to 35-37 ft. lbs. (47-50 Nm).
    2.  
    3. Then tighten them in order to 57-59 ft. lbs. (80-82 Nm).
    4.  
    5. Wait 15 minutes.
    6.  
    7. Tighten them, in order, to 71-73 ft. lbs. (96-100 Nm).
    8.  
    9. Remember to reinstall the bolts that go outside the cylinder head cover and fasten the front of the head to the block at front and rear.
    10.  

  4.  
  5. BMW recommends checking the fit of each tappet in the timing case, by performing the following procedure:
    1. Measure a tappet's outside diameter with a micrometer. Then, zero an inside micrometer at this exact dimension.
    2.  
    3. Then, use the inside micrometer to measure the tappet bore that corresponds to this particular tappet. If the resulting measurement is 0.0001-0.0026 inches (0.002-0.07mm) the tappet may be reused. If it is worn past this dimension, replace it with a new one. If the tappet is being replaced, repeat Steps A and B to make sure it will now meet specifications. If the bore(s) are so worn that even a new tappet would not restore clearance to specification, it would be necessary to replace the timing case.
    4.  
    5. Repeat for all the remaining tappets. Make sure to measure each tappet and its corresponding bore only.
    6.  

  6.  
  7. The remaining steps of installation are the reverse of the removal procedure. Note the following:
    1. Before remounting the timing case, replace the O-ring in the oil passage located at the left/front of the block. Also, check the O-rings in the tops of the spark plug bores and replace these as necessary.
    2.  
    3. Install the timing case and tighten the bolts in several stages. The smaller grade M7 bolts are tightened to 10-12 ft. lbs. (14-16 Nm); the larger grade M8 bolts are tightened to 14.5-15.5 ft. lbs. (19-21 Nm). Install each tappet back into the same bore.
    4.  
    5. When bolting the exhaust pipes to the flange at the manifold, use new gaskets and self-locking nuts and tighten the nuts to 36 ft. lbs. (48 Nm).
    6.  
    7. Then reinstall the intake manifold, check and, if necessary, replace the O-rings where the manifold tubes connect to the throttle necks. Tighten the nuts to 6.5 ft. lbs. (8 Nm).
    8.  
    9. Make sure to refill the radiator and bleed the cooling system.
    10.  

  8.  

M5 and M6 Models

See Figure 25

This is an extremely difficult operation involving the use of a number of special tools. It is necessary to remove both of the camshafts to complete it. Refer to the camshaft removal and installation procedure for information on those special tools.

  1. Mount the engine on a secure engine stand and have the intake and exhaust manifolds removed.
  2.  
  3. Remove the camshafts. Remove the tappets and store them in the order in which they were removed.
  4.  
  5. Remove the pipe that runs along the front of the engine and remove the bolts at the front of the camshaft case.
  6.  
  7. Remove the bolts in and along the camshaft case.
  8.  
  9. Remove the bolts at the front of the cylinder head. Remove the cylinder head bolts starting at the ends of the head and working towards the center in a crisscross fashion.
  10.  

To install:

BMW does not recommend having the head machined.

  1. Make checks of the lower cylinder head and block deck surface to make sure they are true.
  2.  
  3. Lubricate the head bolts with a light coating of engine oil. Make sure there is no oil or dirt in the bolt holes in the block.
  4.  
  5. Install a new head gasket, making sure all bolt, oil, and coolant holes line up correctly.
  6.  
  7. Replace the O-ring in the head at the right/rear where the coolant pipe comes up from the block. Coat the pipe with a suitable sealer.
  8.  
  9. Install the head onto the block. Install the head bolts and tighten in a crisscross fashion starting in the center and working towards the ends. Tighten first to 34.5-37.5 ft. lbs. (48-52 Nm), then to 56.5-59.5 ft. lbs. (78->82 Nm). Wait 15 minutes then tighten to 71-73 ft. lbs. (98-102 Nm).
  10.  
  11. When installing the timing case, replace the O-rings in the small oil passages in the ends of the head. Inspect the O-rings in the center of the block and replace them if necessary. Coat all sealing surfaces with a sealer. Tighten the bolts evenly, torquing the smaller grade M7 bolts to 10-12 ft. lbs. (14-17 Nm) and the larger grade M8 bolts to 14.5-15.5 ft. lbs. (19-21 Nm).
  12.  
  13. Install all lifters back into the same bores.
  14.  
  15. Install the camshafts.
  16.  



Click image to see an enlarged view

Fig. Fig. 25: Cylinder head torque sequence-M5 and M6 models

  1. Reroute the timing chain, as necessary, and remount the drive sprockets for the camshaft. Install the tensioning rail that goes at the top of the timing chain.
  2.  
  3. Install the front cover.
  4.  
  5. Continue to reverse the removal procedure. Note these points:
    1. When reinstalling the intake manifold, inspect the O-rings and replace, as necessary.
    2.  
    3. Refill the cooling system with an appropriate anti-freeze/water mix and bleed the cooling system.
    4.  

  6.  

CLEANING AND INSPECTION



See Figures 26, 27, 28 and 29

Chip carbon away from the valve heads, combustion chambers and ports by using a chisel made of hardwood. Remove the remaining deposits with a stiff brush or a brush attachment for a hand drill.

Aluminum is very soft and is easily damaged. Be very careful not to damage the head. Make sure that the deposits are actually removed, rather than just burnished.



Click image to see an enlarged view

Fig. Fig. 26: Use a gasket scraper to remove the bulk of the old gasket from the cylinder head surface



Click image to see an enlarged view

Fig. Fig. 27: An electric drill equipped with a wire wheel will speed up complete gasket removal



Click image to see an enlarged view

Fig. Fig. 28: Check the cylinder head for warpage along the center using a straightedge and a feeler gauge



Click image to see an enlarged view

Fig. Fig. 29: Be sure to check for warpage across the cylinder head at diagonal points

Clean the remaining cylinder head components in an engine cleaning solvent. Do not remove the protective coating from the valve springs.


WARNING
NEVER "hot tank" a BMW cylinder head, since this process will damage aluminum heads.

Place a straightedge across the gasket surface of the cylinder head. On double overhead camshaft engines, check the camshaft bearing housing surfaces in addition to the gasket surface. Using feeler gauges, determine the clearance at the center of the straightedge. If warpage exceeds 0.0012 inches (0.03mm) over the total length, the cylinder head will require resurfacing. BMW does not recommend resurfacing the M3, M5 or M6 engines cylinder heads. It is acceptable to clean the surface with a whetstone, but the heads should not be ground.

The maximum amount of material removed must not exceed 0.012 inch (0.3mm). The head must be replaced if more material must be removed. Head gaskets with an additional thickness of 0.012 inch (0.3mm) are available to restore the compression ration to standard after the head has been reground.

If warpage exceeds the manufacturer's tolerance for material removal, the cylinder head must be replaced.

Cylinder head resurfacing should be performed by a reputable machine shop in your area. You will need to give the machine shop the stripped head and the front cover. The front cover needs to be machined at the same time as the cylinder head to keep the heights consistent.

 
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