# rb20det compression test 100 psi **URL:** \ **Category:** SON240sx Automotive\ **Created:** [December 4, 2013, 9:05am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131 "2013-12-04T09:05:34Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![RustyS13](https://avatars.discourse-cdn.com/v4/letter/r/b38774/32.png) [@RustyS13](https://forums.speedlife.net/u/RustyS13)\ **Post date:** [December 4, 2013, 9:05am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/1 "2013-12-04T09:05:34Z")
Just got the results on my compression test 100 psi across 5 one cylinder was slightly lower reading 90psi. I am 99% sure the car has a blown head gasket(thick white smoke, muddy bubbling coolant, no power) but my question is would the head gasket be the reason for my low compression readings or is that a sign of other problems in the engine? ---
**Author:** ![G-E](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/g-e/32/5546_2.png) [@G-E](https://forums.speedlife.net/u/G-E)\ **Post date:** [December 4, 2013, 10:35pm UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/2 "2013-12-04T22:35:10Z")
On a 9:1 engine, compression should be 150+ ---
**Author:** ![RustyS13](https://avatars.discourse-cdn.com/v4/letter/r/b38774/32.png) [@RustyS13](https://forums.speedlife.net/u/RustyS13)\ **Post date:** [December 5, 2013, 7:17am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/3 "2013-12-05T07:17:43Z")
> [@G-E](#): > > On a 9:1 engine, compression should be 150+ Any clue where I could be losing that power? my question again… is this because the head gasket is blown or do I have other problems to worry about. ---
**Author:** ![m\_wolfenden](https://avatars.discourse-cdn.com/v4/letter/m/ce73a5/32.png) [@m\_wolfenden](https://forums.speedlife.net/u/m_wolfenden)\ **Post date:** [December 5, 2013, 8:21am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/4 "2013-12-05T08:21:02Z")
well you obviously have some sort of problem…and the first thing you would come to in a teardown is your headgasket and you may be able to tell immediately from that ---
**Author:** ![nate10](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nate10/32/5723_2.png) [@nate10](https://forums.speedlife.net/u/nate10)\ **Post date:** [December 5, 2013, 8:26am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/5 "2013-12-05T08:26:40Z")
Usually if it was your headgasket, it would only be low in 1 or a couple cylinders! I would be leaning towards your piston rings or valve stem seals! Throw some oil in the cylinders as you are doing the compression test, if the comp raises when you put oil in the cylinder your rings are worn. It sounds like a combo of both headgasket and bad rings. ---
**Author:** ![RustyS13](https://avatars.discourse-cdn.com/v4/letter/r/b38774/32.png) [@RustyS13](https://forums.speedlife.net/u/RustyS13)\ **Post date:** [December 5, 2013, 11:00am UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/6 "2013-12-05T11:00:30Z")
> [@nate10](#): > > Usually if it was your headgasket, it would only be low in 1 or a couple cylinders! I would be leaning towards your piston rings or valve stem seals! Throw some oil in the cylinders as you are doing the compression test, if the comp raises when you put oil in the cylinder your rings are worn. It sounds like a combo of both headgasket and bad rings. Yep compression went up quite a lot when i poured oil in ☹ ---
**Author:** ![RustyS13](https://avatars.discourse-cdn.com/v4/letter/r/b38774/32.png) [@RustyS13](https://forums.speedlife.net/u/RustyS13)\ **Post date:** [December 5, 2013, 3:11pm UTC](https://forums.speedlife.net/t/rb20det-compression-test-100-psi/234131/7 "2013-12-05T15:11:13Z")
head is coming off