m20b25 compression test

Need technical Q/A then you're in the right place

Moderator: martauto

Post Reply
bluff467
E30 Zone Newbie
E30 Zone Newbie
Posts: 84
Joined: Fri Oct 30, 2009 11:00 pm
Location: leyland, preston

Thu Jan 27, 2011 8:56 pm

Doing a compression test on my 1991 325i, haven't done one of these before, any advice, (dos and donts)

Chris
Life is short so enjoy it while it lasts. Buy an E30!
bluff467
E30 Zone Newbie
E30 Zone Newbie
Posts: 84
Joined: Fri Oct 30, 2009 11:00 pm
Location: leyland, preston

Fri Jan 28, 2011 8:15 pm

[quote="bluff467"]Doing a compression test on my 1991 325i, haven't done one of these before, any advice, (dos and donts)

Anyways did the cmpression test but I'm a bit confused, (doesn't take much) I got readings of 168 to 175 psi, but thought that they should've read between 142 & 150 psi. Iused a snap-on compression tester. Any advice?
Life is short so enjoy it while it lasts. Buy an E30!
e301988325i
E30 Zone Addict
E30 Zone Addict
Posts: 3701
Joined: Fri Feb 01, 2008 11:00 pm
Location: Taunton, Somerset

Fri Jan 28, 2011 9:54 pm

Did you have the throttle fully open? The main interest with cranking the car over and doing a compression test is a % comparison between cylinders should be <5% difference.

A leak down test will give you much more information, if you are having problems, and haven't found anything wrong.
I said:

Can anyone suggest how to test if the boot lights are staying on with the boot shut?

e30topless said:

lock the wife in there
Post Reply