Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Rocker Arms and Shafts

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REMOVAL & INSTALLATION Diesel Engines



See Figures 1 through 6

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Fig. Fig. 1: To remove the rocker cover arms and shafts, unbolt the venturi linkage and set it to one side



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Fig. Fig. 2: Unfasten the rocker cover retaining bolts ...



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Fig. Fig. 3: ... then remove the rocker arm cover



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Fig. Fig. 4: Remove the old gasket material from the rocker arm cover and cylinder head



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Fig. Fig. 5: Remove the bolts from the rocker arm blocks ...



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Fig. Fig. 6: ... then remove the rocker arm shafts and bolts

Rocker arms on diesel engines can only be removed as a unit with the respective rocker arm blocks.

The 1984 190D does not use rocker arms. The camshaft acts directly on the hydraulic valve tappet.

  1. Detach the connecting rod for the venturi control unit from the bearing bracket lever and remove the bearing bracket from the rocker arm cover.
  2.  
  3. Remove the air vent line from the rocker arm cover and remove the rocker arm cover.
  4.  
  5. Remove the stretchbolts from the rocker arm blocks and remove the blocks with the rocker arms. Turn the crankshaft in each case so that the camshaft does not put any load on the rocker arms.
  6.  

Turn the crankshaft with a socket wrench on the crankshaft pulley bolt. Do not rotate the engine by turning the camshaft sprocket.

  1. Before installing the rocker arms, check the sliding surfaces of the ball cup and rocker arms. Replace any defective parts.
  2.  

To install:
  1. Assemble the rocker arm blocks and insert new stretchbolts.
  2.  
  3. Tighten the stretchbolts. In each case, position the camshaft so that there is no load on the rocker arms. Refer to the previous NOTE.
  4.  
  5. Check to be sure that the tension clamps have engaged with the notches of the rocker arm blocks.
  6.  
  7. Adjust the valve clearance.
  8.  
  9. Reinstall the rocker arm cover, air vent line, and bearing bracket for the reverse lever. Attach the connecting rod for the venturi control unit to the reversing lever.
  10.  
  11. Make sure that during acceleration, the control cable can move freely without binding.
  12.  
  13. Start the engine and check the rocker arm cover for leaks.
  14.  

Gasoline EnginesExcept 190E Models

1976 and later V8's use hydraulic valve lifters.

Before removing the rocker arm(s), be sure that they are identified as to their position relative to the camshaft lobe. They should be installed in the same place as they were before disassembly.

Be very careful removing the thrust pieces. They can easily fall into the engine.

  1. Remove the rocker arm cover or covers.
  2.  
  3. Force the clamping spring out of the notch in the top of the rocker arm. Slide it in an outward direction across the ball socket or the rocker arm.
  4.  

Turn the engine over each time to relieve any load from the rocker arm.

  1. On V8 models, the clamping spring must be forced from the adjusting screw with a small prybar.
  2.  
  3. Force the valve down to remove load from the rocker arm.
  4.  

Don't depress the spring too far. When the piston is up as it should be, the valve will hit the piston. As the spring goes down the thrust piece will fall off into the engine.

  1. Lift the rocker arm from the ball pin and remove the rocker arm.
  2.  

To install:
  1. When installing the rocker arm(s), force the rocker arm down until the rocker arm and its ball socket can be installed in the top of the ball pin.
  2.  
  3. Install the rocker arms.
  4.  
  5. Slide the clamping spring across the ball socket of the rocker arm until it rests in the notch of the rocker arm.
  6.  
  7. On V8 models, engage the clamping spring into the recess of the adjusting screw.
  8.  
  9. Check and, if necessary, adjust the valve clearance.
  10.  
  11. After completion of the adjustment, check to be sure that the clamping springs are correctly seated.
  12.  
  13. Install the rocker arm cover and connect any hoses or lines that were disconnected.
  14.  
  15. Run the engine and check for leaks at the rocker arm cover.
  16.  

190E Models

Rocker arms on this engine are individually mounted on rocker arm shafts that fit into either side of the camshaft bearing brackets.

  1. Remove the cylinder head cover. The cover on the 190E is removed with the spark plug wires and distributor cap still connected.
  2.  
  3. Tag each rocker arm and shaft so that they are identified as to their position relative to the camshaft. They should always be installed in the same place as they were before disassembly.
  4.  
  5. The rocker arm shaft is held axially and rotationally by a bearing bracket fastening bolt. Remove the bolt on the side of the bearing bracket that allows access to the exposed end of the rocker shaft.
  6.  
  7. Thread a bolt (M8) into the end of the rocker arm shaft and slowly ease the shaft out of the bearing bracket.
  8.  


CAUTION
Support the rocker arm/lifter assembly while removing the shaft so it will not drop onto the cylinder head.

Carefully forcing the valve down with a small prybar will remove the load on the hydraulic valve tappet and ease the removal of the shaft. Don't depress the spring too far. When the piston is up as it should be, the valve will hit the piston. As the spring goes down the thrust piece will fall off into the engine.

  1. Replace the bearing bracket bolt and tighten it to 11 ft. lbs. (15 Nm) until ready to replace the rocker shaft.
  2.  
  3. To install, position the rocker arm between the two bearing brackets and slide the shaft into place.
  4.  

The circular groove on the end of the rocker shaft must line up with the mounting bolt shank to ensure proper positioning.

  1. Replace the bearing bracket mounting bolt.
  2.  
  3. Repeat Steps 3-7 for all remaining rocker arm/shaft assemblies. Turn the engine over each time to relieve any load from the rocker arm.
  4.  
  5. Replace the cylinder head cover.
  6.  

 
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