My question pertains to Mercedes engines M116 and 117 and using the “go-no go” gauge in establishing the unloaded “basic position” of the “hydraulic lash compensator” (HLC) a.k.a. as the “hydraulic ball stud assembly".

As experienced by those who have replaced “rocker arms” on these engines, when using the “go-no go” gauge, the “Mercedes Service Manual CD” advises to install the appropriate size “thrust/shim pieces” (a.k.a. as hockey pucks) so that the measuring edge is in the center of the “1.2 mm red measuring groove”. This is the “ideal” basic position of the hydraulic lash compensator.

In practice, however, this “ideal basic position” cannot always be achieved. There are those instances, for example, where the insertion of a 5.1 mm thrust piece causes the “measuring groove”to ride a bit LOWER than ideal (calling for a thinner, 4.75 mm, thrust piece). Then, when the thinner thrust piece is inserted it makes the “red measuring groove” ride a bit HIGHER than ideal. In both cases, the low and high deviations from the ideal position are near equal in magnitude.

When you have the situation described above, what is the best approach: “Is it best to opt for the thicker thrust piece....... or use the thinner thrust piece..........or does it really matter?”

Thank you for responding.