compression test results?

[rockitansky6831]

Here are my compression test results for my '93 525 w/ m50 engine: 85k miles.

1-6: 150, 240, 230, 235, 160, 220 psi.

why are 4 cylinders reading so hi? all should be approx 150 psi right?

[Dave M]

Here are my compression test results for my '93 525 w/ m50 engine: 85k miles.

1-6: 150, 240, 230, 235, 160, 220 psi.

why are 4 cylinders reading so hi? all should be approx 150 psi right?

The absolute values should be taken with a grain of salt. In other words, my compression tester will provide a different result than yours. What is most important, and tell-tale in this case, is the difference between cylinders.

Unless there is a problem with the way the test was conducted (elaborate for us if possible), we see a significant difference in cylinders 1 and 5. On that note, before I went any further interpreting results, I would conduct the test again in hope that something went awry.

Warm engine, throttle wide open etc. etc......... If you are at all in question of 'proper' compression test procedure, we have recently discussed the topic, just try a search.

Keep us informed,

Dave

[e34.535i.sport]

Hey there... Hopefully this will clear a few things up for you:

http://www.bimmernut.com/forum/showthread.php?t=38257&highlight=compression

[Tiger]

Cover up the exhaust tailpipe with your hand and rag and you will feel air rushing out. Same for intake... at the airbox pipe. And if it is from rings, opening the oil filler cap will blow air out.

You must set to engine to certain angle to close both valves before you do the test on each cylinder. The manual will tell you which cylinders at which angle.

[rockitansky6831]

Thx for reply, i added some oil to 2 low cylinders and this increased numbers from #1 cyl 150 to 185 psi, and #5 cyl 160 to 220 psi...........is this enuff info to tell me bad rings?

Also I am conducting a leakdown test. I have tried 3 cylinders now and I hear air escaping but I cant tell if its from exhaust valve or goin to crankcase....how can I narrow these 2 down? thx for help fellas...brian