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

Rocker Arms/Shafts

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INSPECTION



Check the rocker shafts for scoring and wear at the rocker arm pivot points. Check the shaft oiling holes for clogging and varnish. Check the bushing in the rocker arm for wear. Check the adjuster eccentric for flatspots. Check the iron pad for wear and looseness. If the iron pad is loose, it will make a ticking or tapping noise when the engine is running.

REMOVAL & INSTALLATION M20 Engine



The cylinder head must be removed before the rocker arm shafts can be removed. Support the head so it can not move around on the bench.

  1. Disconnect the negative battery cable. Remove the cylinder head.
  2.  
  3. Mount the head on a suitable holding fixture.
  4.  
  5. Remove the camshaft sprocket bolt and remove the camshaft distributor adapter and sprocket. Reinstall the adapter on the camshaft.
  6.  
  7. Adjust the valve clearance to the maximum allowable on all valves.
  8.  
  9. Remove the front and rear rocker shaft plugs and lift out the thrust plate.
  10.  
  11. Remove the spring-clips from the rocker arms by lifting them off.
  12.  
  13. Remove the exhaust side rocker arm shaft:
    1. Set the No. 6 cylinder rocker arms at the valve overlap position (rocker arms parallel), by rotating the camshaft through the firing order.
    2.  
    3. Push in on the front cylinder rocker arm and then turn the camshaft in the direction of the intake rocker shaft, using a 1 / 2 inch drive breaker bar and a deep well socket to fit over the camshaft adapter. Slide each rocker arm to one side as it develops sufficient clearance away from its actuating camshaft and the valve it actuates. Rotate the camshaft until all of the rocker arms are relaxed.
    4.  
    5. Remove the rocker arm shaft by driving it out or pulling it out.
    6.  

  14.  
  15. Remove the intake side rocker arm shaft:
    1. Turn the camshaft in the direction of the exhaust rocker arm.
    2.  
    3. Use a deep well socket and 1 / 2 inch drive breaker bar on the camshaft adapter to turn the camshaft. Slide each rocker arm to one side as it develops sufficient clearance away from its actuating camshaft and the valve it actuates. Rotate the camshaft until all of the rocker arms are relaxed.
    4.  
    5. Remove the rocker arm shaft.
    6.  

  16.  
  17. Install the rocker arm shafts by reversing the removal procedure. Keep the following points in mind:
    1. The large oil bores in the rocker shafts must be installed downward, toward the valve guides and the small oil bores and grooves for the guide plate face inward toward the center of the head.
    2.  
    3. The straight sections of the spring clamps must fit into the grooves in the rocker arm shafts.
    4.  
    5. The guide plate must fit into the grooves in the rocker arm shafts.
    6.  
    7. Adjust the valve clearance.
    8.  

  18.  

M30 Engine See Figure 1

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of the valve train of the M30 engine. The M20 engine is similar in concept

  1. Disconnect the negative battery cable. Remove the cylinder head.
  2.  
  3. Remove the camshaft.
  4.  
  5. Remove the retaining bolts and remove the end cover from the rear of the cylinder head. Slide the thrust rings and rocker arms rearward and remove the snaprings from the rocker arm shafts.
  6.  
  7. Install dowel pins part No. 11 1 063 or equivalent to keep the rocker shafts from turning. Then, remove the rocker shaft oil plugs from the front of the rocker shafts. These require a hex head wrench. Remove the dowel pins. If the rocker shafts have welded plugs, the shafts will have to be pressed out of the head with a tool such as 11 3 050 or equivalent.
  8.  


CAUTION
There is considerable force on the springs positioning the rockers. They may pop out. Be cautious and wear safety glasses.

  1. Install a threaded slide hammer into the end of the rocker shafts and remove.
  2.  

To install:
  1. The rocker arms, springs, washers, thrust rings and shafts should be examined and worn parts replaced. Special attention should be given to the rocker arm camshaft followers. If these are loose, replace the arm assembly. The valves can be removed, repaired or replaced, as necessary, while the shafts and rocker arms are out of the cylinder head.
  2.  
  3. Install the rocker arms in position, noting the following procedures:
    1. Design changes of the rocker arms and shafts have occurred with the installation of a bushing in the rocker arm and the use of 2 horizontal oil flow holes drilled into the rocker shaft for improved oil supply. Do not mix the previously designed parts with the later design.
    2.  
    3. When installing the rocker arms and components to the rocker shafts, install locating pins in the cylinder head bolt bores to properly align the rocker arm shafts. The order of installation is: spring, washer, rocker arm, thrust washer, snapring. Note also that newer, short springs may be used with the older design.
    4.  
    5. Install sealer on the rocker arm shaft retaining plugs and rear cover.
    6.  

  4.  
  5. Install the camshaft and adjust the valve clearance.
  6.  

 
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