BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Timing Chain

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REMOVAL & INSTALLATION M30 Engine



  1. Remove the upper and lower timing chain covers.
  2.  
  3. Turn the engine in the direction of rotation and set cylinder number 1 to tdc.
  4.  
  5. Loosen and remove the camshaft sprocket bolts and remove with the chain. Do not rotate the engine with the timing chain removed.
  6.  
  7. Guide the chain out of the tensioner rails and off the lower sprocket.
  8.  

To install:
  1. Inspect the sprockets for wear and replace if necessary. The bottom sprocket is shrunk on the crankshaft and it is best left to a machine shop to replace. The machine shop will heat the sprocket evenly and pull it off the crankshaft and install it in a similar fashion. The camshaft sprocket is replaced simply with a new unit.
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  3. Install the new chain and the camshaft sprocket. The dowel pin will located at the lower left when looking at it from the front. The bolt holes will be aligned straight up and down, side to side.
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  5. Replace the bolt lock plates if equipped and torque the bolts to 6.5-7.5 ft. lbs. (9-11 Nm). Fold the lock plates up.
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  7. Replace the lower and upper timing covers.
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M42 Engine See Figures 1 through 5

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Fig. Fig. 1: Setting the camshafts to tdc of cylinder 1 engine



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Fig. Fig. 2: Releasing the tensioner piston engine



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Fig. Fig. 3: Compressing the tensioner in a vice to reset it engine



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Fig. Fig. 4: Mounting bolts for the upper chain guide



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Fig. Fig. 5: Once the tensioner is installed, it must be released by pressing back on the tensioner rail engine

  1. Disconnect the negative battery cable. Drain the coolant.
  2.  
  3. Disconnect the coolant hoses and remove the position sensor.
  4.  
  5. Remove the thermostat housing and thermostat. Unscrew the upper timing case cover.
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  7. Remove the crankshaft hub and the lower timing cover.
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  9. Rotate the engine in the direction of the rotation until the camshaft peaks of the intake and exhaust camshafts for cylinder No. 1 face each other. The arrows on the sprocket face up.
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  11. Remove the chain tensioner. Remove the upper chain guide, chain guide bolt on the right side and the sprockets.
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  13. Remove the lower timing chain guide from under the crankshaft sprocket and lift out the timing chain.
  14.  

To install:
  1. Install tool 11 2 300 or equivalent, to hold the crank at tdc. Install tool 11 3 240 or equivalent, to hold the camshafts in proper alignment. If the camshafts have to be turned so much that the valves in cylinders 1 or 4 start to open, turn the crank 90 degrees in the direction of engine rotation. Turn the camshafts and install the tool, then rotate the crankshaft back to tdc. This will prevent the valves from striking the pistons.
  2.  
  3. Install the camshaft sprockets with the arrows pointing up. Torque to 10-12 ft. lbs. (13-17 Nm). Install the timing chain, timing guide bolt on the right side and the upper and lower chain guides.
  4.  
  5. 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 2,697 inch (68.5mm).
  6.  
  7. 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.
  8.  
  9. Install the lower and upper timing covers, crankshaft hub, belts and accessories. Fill and bleed the cooling system. Check the engine oil.
  10.  

M50 Engine See Figures 6, 7 and 8

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Fig. Fig. 6: Inserting the clip to hold the tensioner in the released position engine



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Fig. Fig. 7: Removing the camshaft sprockets engine



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Fig. Fig. 8: Removing the upper chain tensioner engine

  1. Remove the upper timing case cover and the camshaft cover. Crank the engine in the direction of rotation so that the intake and exhaust camshaft peaks for cylinder No. 1 face each other. Hold the camshafts in place with tool 11 3 240 or equivalent. With the camshafts in this alignment the arrows on the sprockets will be facing up. Remove the valve cover mounting studs. Lock the flywheel in place to prevent movement of the crankshaft.
  2.  
  3. Unscrew the chain tensioner and carefully remove. There is a spring contained within the tensioner and may eject out if care is not taken.
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  5. Press down on the upper chain tensioner and lock it into place using tool 11 3 290 or equivalent. Unscrew the transfer timing chain sprockets and pull the 2 off together with the chain. Remove the upper chain tensioner and the lower chain guide. Pull off the main timing chain sprocket along with the chain. Use a bent piece of wire to hold the chain from falling down into the engine. Do not rotate the engine after this point or the valve timing will be disturbed when the engine is reassembled.
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  7. Remove the lower timing chain cover and fold the tensioner rails down. Remove the timing chain.
  8.  

To install:
  1. Install the timing chain on the lower sprocket and on the upper sprocket.
  2.  
  3. Align main timing chain and sprocket on the camshaft so that the arrow faces up. The bolt holes in the camshaft should be on the left sides of the sprocket slots. This will allow the tensioner to take up the slack in the chain and rotate the gear to the counterclockwise position.
  4.  
  5. Install the upper chain tensioner and the lower chain guide. Install the transfer timing gears and chain on the camshafts with the arrows facing up. Make sure that the pulse sender is installed on the intake cam. Do not tighten the sprocket bolts.
  6.  
  7. Install the lower timing chain tensioner with the groove in a vertical position. Use a new sealing ring and torque to 29 ft. lbs. (40 Nm).
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  9. Release the upper timing chain tensioner and torque the sprocket bolts to 16 ft. lbs. (22 Nm).
  10.  
  11. Install the lower timing cover and accessories. Install the upper timing cover.
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  13. Install the valve cover mounting studs and remove the flywheel lock. Install the camshaft cover and the timing case covers using new gaskets. Install the lifting eye and the electrical lead duct. Install the camshaft sensor with a new seal if needed.
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  15. Install the valve cover using new gaskets if necessary. Check that the gasket seats correctly all the way around the seating area.
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  17. Install the ignition coils and connect the electrical leads to each coil.
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  19. Install the thermostat with the arrow or vent facing up with a new O-ring. Install the thermostat housing with a new gasket. Install the intake manifold and throttle valve. Install the exhaust manifolds. Change the oil and check all fluid levels.
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S14 Engine

  1. Disconnect the negative battery cable. Remove the valve cover and lower timing case cover.
  2.  
  3. Remove the distributor cap, rotor and rotor adapter. Remove the distributor housing and the intake camshaft end cover.
  4.  
  5. Remove the socket head bolts holding the upper timing chain guide. Turn the engine in the direction of rotation to tdc of cylinder number 1. Do not move the position of the engine from this point on.
  6.  
  7. Remove the timing tensioner piston. There is strong spring pressure behind the plug.
  8.  
  9. Unfold the sprocket bolt lock plate and remove the sprocket bolts. Remove the sprockets.
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  11. Remove the 2 snaprings for the guide rail, which is located on the left (driver's) side of the engine.
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  13. Pull the guide rail forward and then turn it up to free it from the chain.
  14.  

To install:
  1. Install the timing chain and the guide rail. Install the guide rail snaprings. Place the chain around the lower sprocket
  2.  
  3. Engage the chain with the intake side (E) sprocket with the marks aligned. Turn the intake side (E) sprocket in the direction opposite to normal rotation to tension the timing chain on that side. Bolt this sprocket and the lock plates onto the front end of the intake camshaft. Prevent the camshaft from rotating and torque the bolts to 6-7 ft. lbs. (8-10 Nm). Fold the lock plates up.
  4.  
  5. Engage the timing marks with the mark on the exhaust side (A) sprocket and install the sprocket and lock plates onto the front end of the exhaust camshaft. Use the distributor rotor adapter to keep the sprocket from turning, and torque the bolts to 6-7 ft. lbs. (8-10 Nm). Fold the lock plates up. Make sure the timing chain has stayed in time.
  6.  
  7. Slide the chain tensioner piston into its cylinder. Install a new seal. Now install the spring with the conical end out. Install the cap which retains the spring. Add oil to the well where the piston contacts the tensioner rail. Loosen the nipple on the plug and keep adding oil until oil runs out of the nipple. Close the nipple and torque the cap to 29 ft. lbs. (40 Nm).
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  9. Turn the engine 1 revolution in the normal direction of rotation. Recheck the timing. With the crankshaft at tdc, one groove on each camshaft faces inward and another on each faces the cast boss on the bearing cap.
  10.  
  11. Install the upper timing chain guide. Check and adjust the guide so the chain is centered in the guide.
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  13. Install the timing case cover, distributor housing, distributor rotor adapter, rotor and distributor cap. Install the camshaft end cover and valve cover.
  14.  

S38 Engine

  1. Disconnect the negative battery cable. Remove the valve cover and lower timing case cover. Remove the water pump.
  2.  
  3. Remove the distributor cap, rotor and rotor adapter. Remove the distributor housing and the intake camshaft end cover.
  4.  
  5. Remove the socket head bolts holding the upper timing chain guide. Turn the engine in the direction of rotation to tdc of cylinder number 1. Do not move the position of the engine from this point on.
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  7. Remove the timing tensioner piston. There is strong spring pressure behind the plug.
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  9. Unfold the sprocket bolt lock plate and remove the sprocket bolts. Remove the sprockets.
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  11. Remove the 2 guide pins for the guide rail, which is located on the left (driver's) side of the engine. They are removed by using the flats on the base of the pins as a place to put the wrench. There may be washers under the flats; be careful not to loose them down into the oil pan.
  12.  
  13. Pull the guide rail forward and then turn it up to free it from the chain.
  14.  

To install:
  1. Install the timing chain, guide pins and the guide rail. Place the chain around the lower sprocket
  2.  
  3. Engage the chain with the intake side (E) sprocket with the marks aligned. Turn the intake side (E) sprocket in the direction opposite to normal rotation to tension the timing chain on that side. Bolt this sprocket and the lock plates onto the front end of the intake camshaft. Prevent the camshaft from rotating and torque the bolts to 6-7 ft. lbs. (8-10 Nm).
  4.  
  5. Engage the timing marks with the mark on the exhaust side (A) sprocket and install the sprocket and lock plates onto the front end of the exhaust camshaft. Use the distributor rotor adapter to keep the sprocket from turning, and torque the bolts to 6-7 ft. lbs. (8-10 Nm). Make sure the timing chain has stayed in time.
  6.  
  7. Slide the chain tensioner piston into its cylinder. Install a new seal. Now install the spring with the conical end out. Install the cap which retains the spring. Add oil to the well where the piston contacts the tensioner rail. Loosen the nipple on the plug and keep adding oil until oil runs out of the nipple. Close the nipple and torque the cap to 29 ft. lbs. (40 Nm).
  8.  
  9. Turn the engine 1 revolution in the normal direction of rotation. Recheck the timing. With the crankshaft at tdc, one groove on each camshaft faces inward and another on each faces the cast boss on the bearing cap.
  10.  
  11. Install the upper timing chain guide. Check and adjust the guide so the chain is centered in the guide.
  12.  
  13. Install the timing case cover, water pump, distributor housing, distributor rotor adapter, rotor and distributor cap. Install the camshaft end cover and valve cover.
  14.  

 
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