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Just did compression test...need help

Old Aug 14, 2002 | 01:15 PM
  #1  
BAK12484's Avatar
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From: Shelby Twp., MI, USA
Just did compression test...need help

Did a compression test today after noticing an oil soaked plug in cylinder 3. Well I guess i only did half of a test, as its a bitch to get the hose connected to some of the cylinders - and the lack of time to do so... anyways, here are the results

#1 - 185 psi
#2 - 185 psi
#3 - 205 psi
#4 - 187 psi

obviously it shows that there is something going on w/ cylinder 3...but am wondering why it has a higher compression than the other cylinders?? Is it because of the oil in it??

Also, after the test i was holding it at different rpm's and revving it and seeing if i could hear anything. Well besides the hesitation problem when go full throttle, i noticed that if i stepped on it and held until around 3500, there would be quite a bit of blue smoke, accompanied by the smell of burnt oil

So...if somebody could please interpret these results, i'd appreciate it.
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Old Aug 14, 2002 | 01:48 PM
  #2  
rezinn's Avatar
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From: California
Despite #3 being off by a bit, those results are decent. You're probably right about the oil in #3 causing the higher reading. To get an accurate reading all cylinders need to be dry. You need to find out where the oil is getting in, I'd guess it's a bad seal. Anything done to the engine recently?
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Old Aug 14, 2002 | 01:48 PM
  #3  
RB83L69's Avatar
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Joined: Jul 1999
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
A high reading on one cylinder usually indicates either an intake valve train problem, such that the intake duration on its closing side is too low; or on the exhaust side, such that the valve basically doesn't open at all. Usually it's a rolled cam lobe. It looks to me like an intake valve situation.

With the numbers you give, I'm guessing it's either a LG4 or a L03 or a TPI auto, since the cam is obviously a very low-duration one. It looks like a peanut-cammed engine.

As far as the smoke, I'd bet it's valve guide seals. If you haven't replaced them, they're toast, just like everybody else's.

I don't think the smoke and comrpession readings are related in any way.
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