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Re: LOW COMPRESSION, PLS HELP!!! (archive)

[ Follow Ups ] [ 5-series (E34) Message Board ] [ Msg. Board FAQ ]

Posted by Luc on February 22, 2000 at 11:19:12:

In Reply to: LOW COMPRESSION, PLS HELP!!! posted by Edgar on February 22, 2000 at 08:42:24:

These values are in bar and they don't look good. I believe the BMW maximum allowed difference between the highest and lowest value should not exceed 0.5 bar (about 7 psi) for an engine in top shape. Other sources say: the lowest value should be at least 75% of the highest value, which is in your case 6.75 bar, which means your engine fails. I think the 0.5 bar rule may be asking too much from a (well used?) engine, but the differences allowed with the 75% rule would have me worried. We're talking high tech engines here. I would like to see all values within 1 bar of each other. 11 bar is indeed the value to look for (on a good engine) so even your best value of 9 bar is of. 7 and 6 bar values are definetely no good and need fixing.
How was the test done? Was the compression tester a push-on type or a screw-in type? The push-on type allows for bad sealing at the spark plug hole and is not reliable. Have it done properly (by another dealer?) with a screw-in tester.
Try using valve cleaner for a few weeks and do the test again. You'll be surprised by the difference.
Luc.




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