BenzWorld Senior Member
Date registered: Jun 2004
Mentioned: 0 Post(s)
Quoted: 17 Post(s)
I'm fairly certain your car has hydraulic valve lifters. I worked on a 1975 or 1976, and remember reading that the next year Mercedes went to hydraulic. It is true and not true that there is no adjustment. There is no major adjustment, but there are shims on top of the valve stems that adjust the lifters to get them all to the same height from the head. If they are not hydraulic, then they definitely can be adjusted, and should be.
I doubt the shims are an issue here, but it is possible a hydraulic valve lifter has gone bad and has collapsed. It does happen, and they are replaceable. A good mechanic can take the valve cover off and check each to make sure it is working properly. The wrist pin noise is possible, but sounds like he is just guessing. There is a tool that looks like a stethoscope that can be used to pinpoint the location of a noise without guessing.