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Old 02-11-2011, 09:05 AM
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bluebee bluebee is offline
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Location: San Jose, California
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Mein Auto: 02 BMW 525i M54 auto 130K
Originally Posted by 540alex View Post
why would they start leaking and is it possible that they are all leaking almost the same
Those numbers don't look too badly off. I don't know what percentage is considered abnormal - maybe someone has a spec for what the percentage off between cylinders for the BMW so you can judge against the spec?

As for what could cause loss of compression ... just one idea is a DISA valve ... which there are a few threads on ... where parts get sucked into the intake manifold, and from there into the cylinders where they are destroyed and sucked out the exhaust manifold.

There are pictures here:
- Example of how a DISA valve can ruin your engine compression (1)

But, I would think there is a well-defined test sequence for what causes the loss of compression below spec (I don't have it though ... so if/when you find it, send it my way and I'll add it to the best links thread for others to benefit from).

Last edited by bluebee; 02-11-2011 at 09:06 AM.
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