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

Oil Pump

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REMOVAL M20 Engine



  1. Remove the oil pan to expose the oil pump.
  2.  
  3. Remove the oil pump mounting bolts and the oil pump support mounting bolts.
  4.  
  5. Lower the oil pump and the drive shaft.
  6.  

M30 Engine

  1. Remove the oil pan to expose the oil pump.
  2.  
  3. Remove the sprocket mounting nut and pull the sprocket from the shaft. The nut is left hand threaded.
  4.  
  5. Remove the oil pump mounting bolts.
  6.  
  7. Lower the oil pump.
  8.  

M42 Engine See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Oil pump cover mounting bolts in the timing cover engine

  1. The oil pump is part of the timing case. It is necessary to remove the front timing cover, timing chain and sprockets to access the timing case.
  2.  
  3. Remove the front cover, timing chain, guides and sprockets. The oil pump is integral to the timing case.
  4.  
  5. Remove the 4 bolts to remove the oil pump cover. Be careful not to drop the inner and outer rotors.
  6.  

M50 Engine

  1. Remove the lower oil pan to expose the oil pump. Remove the upper oil pan mounting bolts.
  2.  
  3. Remove the sprocket mounting nut and pull the sprocket from the shaft. The nut is left hand threaded.
  4.  
  5. Remove the oil pump mounting bolts.
  6.  
  7. Lower the oil pump and pan.
  8.  

S14 and S38 Engines

  1. Remove the oil pan to expose the oil pump.
  2.  
  3. Remove the sprocket mounting nut and pull the sprocket from the shaft. The nut is left hand threaded.
  4.  
  5. Remove the oil pump mounting bolts and the oil pump support mounting bolts.
  6.  
  7. Lower the oil pump.
  8.  

INSPECTION Except M42 Engine



Check that the oil pump turns freely and without binding. Check that the oil pump pickup screen is not clogged. Check the condition of the drive sprocket on chain driven pumps.

While the pumps can be disassembled and checked for wear, it is more common to replace the oil pump if it has seen long service. If the pump is to be disassembled, be sure that new gaskets are available before disassembling the pump body.

If the drive sprocket is found to be worn as indicated by pointy teeth, replace the chain at the same time. The sprocket and the chain will wear at the same rate. In cases of severe wear, the crankshaft gear may need to be replaced also. This will require the crankshaft to be removed.

Depress the oil pressure relief valve washer and remove the snapring. Measure the free length of the spring and check that the piston can move freely. The valve is contained in the body of the oil pump.

M42 Engine See Figure 2

Click image to see an enlarged view

Fig. Fig. 2: Inspecting the oil pump gears engine

  1. Remove the timing case.
  2.  
  3. Remove the cover from the pump rotors. Make note of the positioning of the rotors.
  4.  
  5. Measure the play between the pump body and the outer rotor; outer rotor and inner rotor. The distance should be 0.005-0.008 inch (0.12-0.20mm).
  6.  
  7. The marks on the rotors face up and the rotors should be placed in the original orientation as removed. Replace the cover assembly and tighten to 6-7 ft. lbs. (8-10 Nm).
  8.  
  9. Depress the oil pressure relief valve washer and remove the snapring. Measure the free length of the spring and check that the piston can move freely.
  10.  
  11. Replace the timing case.
  12.  

INSTALLATION M20 Engine



  1. Replace the oil pump drive shaft bearing:
    1. Remove the clamp bolt holding the pump drive shaft. This is located on the side of the engine where the distributor used to be mounted on non-dme equipped vehicles.
    2.  
    3. Pull the cover with the gear out of the bore. Check the condition of the O-ring and replace if necessary.
    4.  
    5. Use bmw tool 11 1 310 or equivalent, to drive out the needle bearing out through the top of the bore.
    6.  
    7. Lubricate the new needle bearing with grease and install with bmw tool 11 1 300 or equivalent. Drive the bearing into the bore until fully seated.
    8.  
    9. Install the gear and cover.
    10.  

  2.  
  3. Fill the oil pump pressure side with oil.
  4.  
  5. Install the oil pump and guide the drive shaft up into the drive gear. Torque the bolts to 15-17 ft. lbs. (20-24 Nm).
  6.  

M30, M50, S14 and S38 Engines

  1. Install the oil pump on the engine. Tighten the pump to block bolts, then the support bolts. Torque the bolts to 15-17 ft. lbs. (20-24 Nm).
  2.  
  3. Place the pump drive chain around the drive sprocket and slide over the pump shaft. Torque the nut to 18-21 ft. lbs. (25-29 Nm).
  4.  
  5. Check the slack in the drive chain. The chain should have slight play when depressed with thumb pressure.
  6.  
  7. If the chain is too loose, add oil pump mounting shims between the pump and engine block mounting. The shims are available at your dealer or parts supplier. Match the bore in the shim with the bore in the block.
  8.  

M42 Engine

The oil pump in the M42 engine is integral with the timing case.

  1. Replace the gasket and install the timing case. The lubrication spray nozzle faces the bolt.
  2.  
  3. Replace the timing chain and sprockets. Install the timing covers.
  4.  

 
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