PeachParts Mercedes-Benz Forum - Testing HLC on M116 M117 engines

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Testing HLC on M116 M117 engines

On a 1989 420SEL, how does one test the hydraulic lash compensators (HLC)?

I read the service manual and it said to press down on them and if one drops faster than the rest, then the fast dropping one should be replaced. But when I pressed down on the HLCs, they did not move a millimeter. Could they be filled with sludge or frozen?

I removed 4 HLCs, soaked them in gasoline, and they were still rock hard. Then I used a C-clamp to squeeze them down, several times. Now 3 of the 4 can be pressed down a few millimeters with force exerted by one's thumb. The fourth can only be compressed using the c-clamp.

Comments?

If a lifter is "bad" then you will be able to push then down with very little force. HOWEVER if they are only out of adjustment they will be tight.

How does one adjust a HLC? Should the ball be turned to increase or decrease the return pressure?