Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Hydraulic Valve Lifters

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CHECKING BASE SETTING



See Figure 1

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Fig. Fig. 1: Cross-sectional view of the valve train, revealing the hydraulic lifter location and its related components

Hydraulic valve lifters are used with overhead cams on 1976 and later V8 engines. The rocker arm is always in contact with the cam, reducing noise and eliminating operating clearance.

A dial indicator with an extension and a measuring thrust piece (MBNA #100 589 16 63 00, 0.187 in. thick are necessary to perform this adjustment.

1976-84 V8 Engines See Figures 2 and 3

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Fig. Fig. 2: Measuring the thrust piece



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Fig. Fig. 3: Selective thrust pieces

The base setting is the clearance between the upper edge of the cylindrical part of the plunger and the lower edge of the retaining cap (dimension A) when the cam lobe is vertical.

  1. Turn the cam lobe to a vertical position.
  2.  
  3. Attach a dial indicator and tip extension and insert the extension through the bore in the rocker arm onto the head plunger. Preload the dial indicator by 2 mm and zero the instrument.
  4.  
  5. Depress the valve with a valve spring compressor. The lift on the dial indicator should be 0.028-0.075 inch.
  6.  
  7. If the lift is excessive, the base setting can be changed by installing a new thrust piece.
  8.  
  9. Remove the dial indicator.
  10.  
  11. Remove the rocker arm.
  12.  
  13. Remove the thrust piece and insert the measuring disc.
  14.  
  15. Install the rocker arm and repeat Steps 1-3.
  16.  
  17. Select a thrust piece according to the table. If the measured value is 0-0.002 inch and the 0.2146 inch thrust piece will not give the proper base setting, use the 0.2883 inch thrust piece.
  18.  
  19. Remove the dial indicator and the rocker arm. Install the selected thrust piece.
  20.  
  21. Reinstall the rocker arm and dial indicator and repeat Steps 1-3.
  22.  

REMOVAL & INSTALLATION



Temporarily removed valve lifters must be reinstalled in their original locations. When replacing worn rocker arms, the camshaft must also be replaced. If the rocker arm, or hydraulic lifter is replaced, check the base setting.

Remove the rocker arm and unscrew the valve lifter with a 24 mm socket.

 
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