Compression Experts Please Help!! - PeachParts Mercedes-Benz Forum

GRIESL · #1 12-12-2006, 08:56 PM

Quote:

Originally Posted by davidh

we use to use the downhill test to check for bad rings. de-acceleration for an entended down hill trip and at the bottome of the hill if the rings were bad, you would have blue smoke on take-off. lots of it. it would accumulate the unburned oil as you traveled down using the engin compresion as a brake, kinda. does this make sense to you ? hard to explain. we have a main street hill thats a bit over a mile long and did this when we wanted to check for bad rings. . .

Makes sense, thanks. I live up a pretty big hill and I shift into S sometimes to give the brakes a rest, but also when the engine is cold to warm her up. I've noticed any more smoke than usual in that case.

Also, someone mentioned turbo seals. I thought bad turbo seals would not cause excessive smoke at idle (which is what I have) but that the oil would accumulate in the turbo and wait for the next wallop of air when you hit the accelarator.

thorsen · #2 12-13-2006, 08:00 AM

Quote:

Originally Posted by GRIESL

Also, someone mentioned turbo seals. I thought bad turbo seals would not cause excessive smoke at idle (which is what I have) but that the oil would accumulate in the turbo and wait for the next wallop of air when you hit the accelarator.

Bad turbo seals would not cause low compression.

t walgamuth · #3 12-15-2006, 04:37 PM

a badly worn cam could be not letting a full charge of air in if the intake lobes are so worn it is not staying open long enough.

i suggest you take the valve cover off and have an experienced machinist look at the camshaft. you can look as well, if it is off that much it may be pretty easy to see.

with compression figures so low i would think the performance would be terrible. rough idle too.

i suspect the compression test. it may be giving you bad readings.

i wouldn't pull the head just yet.

tom w