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Compression differences

The discussion of head gaskets got me going to my '89 300E to get it ready for potential driving soon. I squirted a bit of oil in the cylinders, let them sit for a bit turning engine by hand and with the plugs out have now cranked the engine... no problem, nothing seized. Soooo, I thought might as well test compression as long as the plugs are out. The result is

125, 145, 175, 150, 149, 135 can't remember what 'reasonable' differences might be, in particular I wonder about cylinder #1 I'm going to wait a bit longer just in case the oil hasen't coated the cylinder walls properly yet and I'll try again... don't expect much difference though. Is the engine getting marginal?

cheers

ps will still not sell it if repairs are needed. We will NEVER find another car that is as easy and pleasant to work on. I guess you've got to love cars to keep these old ones. BTW to the person trying to decide re selling, never, oh, never listen to your wife. They are all the same in wanting you to get rid of old stuff... gee, I've got a perfectly good 10 year old shirt that I really like which the wife is cosntantly trying to get rid of and I've got to continually rescue it :-)

Reply to
Guenter Scholz
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Don't put oil into cylinder to test for compression.

You stop engine cranking after the third jump on the compression gauge.

10% differential between adjacent cylinders is acceptable.

It must be at least 100 PSI to pass emission.

As long your engine ran the day before the test is all you need. Engine temperature is just warm... not hot.

My 124 is 95 E300D... I love it even though it needs some work to get it to perfection. It is a pleasure to drive that car. Lots of love will happen soon.

Reply to
Tiger

thanks for the points, I put the oil into cylinders simply in case that they might have seized after sitting for a couple of years without having started the engine.

So, I imagine that since I had put some oil in all the cylinders I should repeat the test after the oil I squirted in has had a chance to leak out. I imagine turning engine over a few times, without starting, should clear out any excess oil after a few days.

good to know about the 100psi minimum, I'm guessing since just one cylinder was dangerously low at 125 psi I may have a burned exhaust valve.

cheers

Reply to
Guenter Scholz

You need to run the engine so it is normalized... you know after sitting so long... something is possibly sticking.

After engine is running, then check compression.

Reply to
Tiger

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