Valve adjustment, easy fix, or is it?

[sharpshooter677]

Hi all,

I have a 74 2.0. Recently, a pretty severe knocking was coming from my motor. As expected, it required a simple valve adjustment, which was done by my normal vw guy. I drove it for a few months until I needed to go back as it had redeveloped... I noticed the knocking come back after roughly 3 months from the initial Val e adjustment. I took it back to my mechanic for a second time for a quick fix again, but a couple days later, the knocking is back. My mechanic claims this is due to a cam issue, but ensured that it was fine to drive. What is the worst case scenario? Could he just not want to perform a valve adjustment at his cost? Any help is appreciated. Thank you.

[Dave at Pelican Parts]

Worst case, it is a cam issue. The cam is going flat, sending lots of debris through the oil system. Or a lifter is, with pretty much the same result. Repair involves taking the engine all the way apart and basically doing a complete rebuild.

More likely is that the valve adjusting lugs have worn significantly, and are no longer smooth and rounded at the end. This makes getting the adjustment difficult, and since the hardened layer is very thin, the wear only gets quicker. This results in less material going through the oil system, but is not exactly fun. The lugs themselves are easy to replace when you do a valve adjustment. I don't remember them being very cheap, though.

Another possibility is that the valve tips have worn. When the valves rotate (as they are supposed to do), the clearance changes. You can band-aid this by putting hardened caps on the valve tips, but it usually means the valves are pretty worn. The real fix would be pulling the heads and replacing the valves. More expensive than new adjusting lugs, not as much as a full rebuild.

There are other possibilities, like valves stretching right before they break and the motor sends a piece of one all the way through the head, or the holes in the rocker arms getting stripped by over-enthusiastic torquing, or the rocker arm shaft retaining nuts not being quite tight enough, or...

I would want to figure out what is going on before I just drove it, though.

--DD

[sharpshooter677]

Wow dave as informative as that was, it wasn't the best news. Thank you very much though I will look into the possibilities.