Valve Clearance Adjustment. What am I Doing Wrong?

[73MB280SEL]

While I had the valve covers off last weekend, I took the time to measure my valve clearance. What I found was good and not so good. One camshaft is obiously worn and probably is heading for replacment. One of this cam's lobes looks like it has worn through the case hardening and has devaloped a slight ridge. The other one has obviously been replaced at some time in the past.

Problem is that the replaced cam has its clearance set way too tight. One of the lobes has polished 360 degrees (no more yellow coating to be seen). This could be a valve failure, I just don't know at this point. I'd like to adjust it, however, just to see if it works reasonably well.

So I tried to adjust the valves with a 17 MM wrench on the ball stud and could not budge any of them either direction. I now have a crows foot and an offset extension as required by the service manual and will try again, but I'm concerned that I'm not doing something correctly.

Should these be very tight? Seems like the torque spec on them is 20 - 40 Nm. I don't have my conversion chart in front of me, but that isn't too many lbs-ft (<50).

The last thing I'd want to do is round the nut off or break something.

Sholin

------------------
Lt. Blue 1973 MB 280 SEL (108) with sunroof and console shift.
1996 Chevy Camaro Z-28 LT1.

[ctaylor738]

Obviously these have not been adjusted for some time! I had a 250C in the same condition. The dealer had a way to soak the adjusters in penetrating oil overnight to loosen them up. I don't know what tool you are using, but I personally would be willing to move up to a 1/2" breaker bar - they can be pretty stubborn.

Chuck

[73MB280SEL]

Thanks,

That's exactly what I did. I bought the Sir Tools offset 1/2-inch extension and used my crows foot along with a big-ol honkin' 1/2-inch Craftsman ratchet.

Man, what a difference getting the clearance set correctly makes. Runs much better now.

This weekend I'm going to recheck them to make sure I did everything correctly. I have to replace the ancient rubber valve cover gaskets anyway.

Sholin in Mustang, OK.

------------------
Lt. Blue 1973 MB 280 SEL (108) with sunroof and console shift.
1996 Chevy Camaro Z-28 LT1.

[This message has been edited by 73MB280SEL (edited 11-24-2000).]