Symptoms of a Bad Valve Adjustment? - PeachParts Mercedes-Benz Forum

Squabble · #1 05-06-2012, 07:12 AM

hey all, just wanted to find out what the symptoms of a bad valve adjustment could be? specifically on a euro m110 if that changes anything.

adjusted my valves less than 1k miles ago and the engine just seems "clackety" or "chattery." it might be in my head but it just seems a little noisy. then again, i have no real idea of how these engines "should" sound when tuned properly, the two i've owned are the only ones i've heard in the wild. listening to them on youtube i can't get a sense of what's proper, what's not, and what's just crappy microphone sound.

daddi · #2 05-06-2012, 09:35 AM

The problem is not in your head it's in the engines head, the balls on the end of the adjustment bolt are starting to wear out. When you adjust the valves the wear grooves are misaligned and after a short while there to much valve clearance again. The only way to fix this permanently is to replace the adjustment bolts and the rocker arms.

Squabble · #3 05-06-2012, 11:30 AM

Quote:

Originally Posted by daddi

The problem is not in your head it's in the engines head, the balls on the end of the adjustment bolt are starting to wear out. When you adjust the valves the wear grooves are misaligned and after a short while there to much valve clearance again. The only way to fix this permanently is to replace the adjustment bolts and the rocker arms.

even at such low mileage?

daddi · #4 05-06-2012, 11:39 AM

I've seen this with even lower mileage, may have something to do with the oil pressure. I've not done a big search for the cause.

RANDY P · #5 05-06-2012, 05:30 PM

Mine is like that untll it's fully heated up- better a slightly loose valve than one too tight.

No oil consumption, no funny drivability issues, fine with me the way it is.

M110 USA with 76K on it.

daddi · #6 05-06-2012, 06:32 PM

One of my customers has a 280E '80 with 300,000 miles on it, valve adjustment is done once a year. This problem has not shown itself in that car.

RANDY P · #7 05-06-2012, 08:20 PM

I guess we really need to define "noisy"- At worst my car has a consistent mechanical valvetrain sound, and it settles down in volume once the car has been running at temp for awhile. It sounds even.

I have it adjusted by the book.

280EZRider · #8 05-07-2012, 12:24 AM

I adjusted the valves on that engine for the former owner sometime last summer. They were not very far out of adjustment to begin with.

That being said, yes, the M110 will be noisy at idle because it's a high RPM engine. Most engines don't cruise at 4000 RPM + like the M110, so naturally the valves need plenty of clearance at lower RPM to allow for valve-stem stretch at high speed. As long as they are not noisy at the higher RPM speeds, you're OK. And as previously mentioned, even if they are out of adjustment, better to be on the noisy side than the quiet burn-the-valve side.

I suspect you took the car to a mechanic, the car sat for an hour or so, and the valves were then adjusted. Did he use hot or cold clearance specs? The only way to accurately adjust engine valves is to allow the engine to sit over night to completely cool (M110 valves are at the very top of the engine and be the last thing to cool) and use the cold specs doing the adjustment next day.