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

Timing Chain Cover

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REMOVAL & INSTALLATION M30 Engine



  1. Disconnect the negative battery cable. Remove the cylinder head cover. Remove the distributor cap, rotor and rotor adapter.
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  3. Drain the coolant to below the level of the thermostat and remove the thermostat housing cover.
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  5. Remove the mounting bolts and note the lengths and positions of the bolts. Remove the upper timing case cover.
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  7. Remove the fan, vibration damper and hub. Remove the water pump pulley. The power steering pump must be removed, leaving the pump hoses connected and supporting the pump out of the way but so the hoses are not stressed.
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  9. Remove the piston which tensions the timing chain, working carefully because of very high spring pressure.
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  11. Detach the tdc position sender.
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  13. Loosen all the oil pan bolts, and then unscrew all the bolts from the lower timing case cover, noting their lengths for reinstallation in the same positions. Carefully, use a sharp bladed tool to separate the gasket at the base of the lower timing cover. Then, remove the cover.
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To install:
  1. Check the condition of the oil pan gasket; replace if necessary. To install the lower cover, first coat the joints of the oil pan and block with sealer. Put it into position on the block, using new gaskets.
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  3. Install the tensioning piston with the conical end of the spring against the plug. Install all bolts; then tighten the lower front cover bolts evenly; finally, tighten the oil pan bolts evenly. Torque the timing cover M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm). Tighten the oil pan M6 bolts to 6.5-8.0 ft. lbs. (9-11 Nm) and the M8 bolts to 13-15 ft. lbs. (18-22 Nm).
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  5. To bleed the tensioner, fill the tensioner pocket where the piston contacts the tensioner rail with oil. Loosen the plug a few threads and move the tensioner rail back and forth until oil comes out of the plug threads and resistance is felt. Tighten the plug to 21-29 ft. lbs. (30-40 Nm).
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  7. Inspect the hub of the vibration damper. If the hub is scored, install the radial seal so the sealing lip is in front of or to the rear of the scored area. Lubricate the seal with oil and install it with a sealer installer.
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  9. Install the pulley/damper and torque the bolt to specifications. When installing, make sure the key and keyway are properly aligned. Install the tdc transmitter and its mounting bracket.
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  11. Install the power steering pump and water pump pulley. Reinstall and tension all belts.
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  13. Just before installing the upper timing case cover, check the condition of that area of the head gasket. It will usually be in good condition. If it should show damage, it must be replaced.
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  15. Before installing the upper cover, use sealer to seal the joint between the back of the lower timing cover and block at the top. On some vehicles, there are sealer wells which are to be filled with sealer. If these are present, fill them carefully. Install new gaskets. Check the seal at the distributor drive and replace it, if necessary.
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  17. Note that the top bolt on the driver's side and the bottom bolt on the passenger's side are longer. Tighten the 2 bolts that run down into the lower timing cover first to finger tight; torque the 6 bolts, then torque the bottom bolts. Torque the timing cover M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm).
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  19. Inspect the sealing O-rings and replace, as necessary. Make sure the bolt at the center of the rotor has its seal in place and torque to 16-17 ft. lbs. (22-24 Nm). Install the rotor and distributor cap.
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  21. Install the cylinder head cover. Install the thermostat and housing with a new O-ring. Fill the cooling system with coolant and bleed.
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M42 Engine

  1. Remove the ignition leads and valve cover. Remove the cam position sender on the upper cover. Drain the coolant and remove the thermostat housing. Remove the thermostat.
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  3. Remove the 11 bolts holding the upper timing cover. Remove the cover carefully to avoid damaging the head gasket.
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  5. Remove the radiator, fan, belts and water pump pulley. The water pump does not need to be removed to remove the lower cover.
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  7. Remove the damper and the crankshaft hub.
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  9. Remove the 21 bolts and remove the cover.
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To install:
  1. Check the engine block dowel sleeves. Install new gaskets on the cover. Check the condition of the radial seals and replace if necessary.
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  3. Install the cover and torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm).
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  5. Install the crankshaft hub and damper. Install the water pump pulley and belts. Install the fan and radiator.
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  7. Place sealer at the head gasket to cover joints. Place the upper cover with new gaskets. Install 2 bolts and press the upper cover into place by wedging down against the camshaft sprocket. Torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm).
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  9. Install the valve cover and ignition leads. Install the thermostat and cover. Install the cam position sender. Fill the cooling system with coolant mixture and bleed.
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M50 Engine

  1. Remove the ignition coils and valve cover. Drain the coolant and remove the thermostat housing. Remove the thermostat.
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  3. Remove the 8 bolts holding the upper timing cover. Remove the cover carefully to avoid damaging the head gasket.
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  5. Remove the radiator, fan, belts and water pump pulley. The water pump does not need to be removed to remove the lower cover.
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  7. Remove the damper and the crankshaft hub.
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  9. Remove the 13 bolts and remove the cover.
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To install:
  1. Check the engine block dowel sleeves. Install new gaskets on the cover. Check the condition of the radial seals and replace if necessary.
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  3. Install the cover and torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm).
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  5. Install the crankshaft hub and damper. Install the water pump pulley and belts. Install the fan and radiator.
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  7. Place the upper cover with new gaskets. Torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm).
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  9. Install the valve cover and ignition coils. Install the thermostat and cover. Fill the cooling system with coolant mixture and bleed.
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S14 Engine

  1. Disconnect the negative battery cable. Drain the cooling system through the bottom of the radiator. Remove the radiator and fan.
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  3. Disconnect all electrical plugs, remove the attaching nuts, and remove the air cleaner and airflow sensor.
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  5. Note and, if necessary, mark the wiring connections. Then, disconnect all alternator wiring. Unbolt the alternator and remove it and the drive belt.
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  7. Unbolt the power steering pump. Remove the belt and then move the pump aside, supporting it out of the way but in a position where the hoses will not be stressed.
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  9. Remove the 3 bolts from the bottom of the bell housing and the 2 bolts below it which fasten the reinforcement plate in place.
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  11. Remove the drain plug and drain the oil from the lower oil pan. Then, remove the lower oil pan bolts and remove the lower pan.
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  13. Remove the 3 bolts fastening the bottom of the front cover to the front of the oil pan. Loosen all the remaining oil pan bolts so the pan may be shifted downward just slightly to separate the gasket surfaces.
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  15. Remove the water pump. Remove the center bolt and use a puller to remove the crankshaft pulley.
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  17. Remove the piston for the timing chain tensioner.
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  19. Remove the bolts attaching the top of the front cover to the cylinder head. Then, remove all the bolts fastening the cover to the block.
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  21. Run a sharp bladed tool carefully between the upper surface of the oil pan gasket and the lower surface of the front cover to separate them without tearing the gasket. If the gasket is damaged, remove the oil pan and replace it.
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To install:
  1. Before reinstalling the cover, use a file to break or file off flashing at the top/rear of the casting on either side so the corner is smooth. Replace all gaskets, coating them with silicone sealer. Where gasket ends extend too far, trim them off. Apply sealer to the area where the oil pan gasket passes the front of the block.
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  3. Slide the cover straight on to avoid damaging the seal. Install all bolts in their proper positions. Coat the 3 bolts fastening the front cover to the upper oil pan with the proper sealant.
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  5. Tighten the bolts at the top, fastening the lower cover to the upper cover first. Then, tighten the remaining front cover bolts and, finally, the oil pan bolts to 7 ft. lbs. (9 Nm). Torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm). Inspect the sealing O-rings and replace, as necessary. If it uses the dme distributor with the screw-off type rotor, make sure the bolt at the center of the rotor has its seal in place and that it is installed with a sealer designed to prevent the bolt from backing out.
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  7. Torque the oil drain plug to 24 ft. lbs. (32 Nm) and both upper and lower oil pan bolts to 7 ft. lbs. (10 Nm).
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  9. Reverse the remaining portions of the removal procedures, making sure to fill and bleed the cooling system and to refill the oil pan with the correct oil.
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S38 Engine

  1. Disconnect the negative battery cable. Pull out the plug and remove the wiring leading to the airflow sensor. Loosen the hose clamp and disconnect the air intake hose. Remove the mounting nut and remove the air cleaner and airflow sensor as an assembly.
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  3. Remove the radiator and fan. Remove the damper and hub.
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  5. Remove the pipe that runs across in front of the front cover. Remove the mounting bolts and remove the water pump pulley.
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  7. Loosen the top/front mounting bolt for the alternator. Remove the lower/front bolt. Loosen the 2 side bolts. Swing the alternator aside.
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  9. Remove the power steering pump mounting bolts. Make sure to retain the spacer that goes between the pump and oil pan. Swing the pump aside and support it so the hoses will not be under stress.
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  11. Remove the bolts at the top, fastening the lower front cover to the upper front cover. Remove the bolts at the bottom, fastening the lower cover to the oil pan. Loosen the remaining oil pan mounting bolts.
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  13. Run a sharp bladed tool carefully between the upper surface of the oil pan gasket and the lower surface of the front cover to separate them without tearing the gasket.
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  15. Loosen and remove the remaining front cover mounting bolts, noting the locations of the tdc sending unit on the upper/right side of the engine and the suspension position sending unit on the upper left. Also, keep track of the bolts that mount these accessories, as their lengths are slightly different. Remove the timing cover, pulling it off squarely.
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To install:
  1. Before reinstalling the cover, use a file to break or file off flashing at the top/rear of the casting on either side so the corner is smooth. Replace all gaskets, coating them with silicone sealer. Where gasket ends extend too far, trim them off. Apply sealer to the area where the oil pan gasket passes the front of the block.
  2.  
  3. Slide the cover straight on to avoid damaging the seal. Install all bolts in their proper positions. Tighten the bolts at the top, fastening the lower cover to the upper cover first. Then, tighten the remaining front cover bolts and, finally, the oil pan bolts. Torque the M6 bolts to 6-7 ft. lbs. (8-10 Nm) and the M8 bolts to 15-17 ft. lbs. (20-24 Nm). Inspect the sealing O-rings and replace as necessary. If it uses the dme distributor with the screw-off type rotor, make sure the bolt at the center of the rotor has its seal in place and that it is installed with a sealer designed to prevent the bolt from backing out.
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  5. Complete the installation procedure, making sure to refill and bleed the cooling system.
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