Compression issue or not?

[mrd05d]

So i ran a compression test today on my 96 Camaro 3.8 and got these numbers. What do you think they mean...


1 - 185 PSI
2 - 185 PSI
3 - 165 PSI
4 - 185 PSI
5 - 175 PSI
6 - 185 PSI

So this is the first time ive done a compression test but since 3 and 5 are next to each other and are lower does that mean a head gasket issue?

Also If not does 3 have any issues or is everything pretty much normal for a 3.8 with 95k miles on it?

If you read my other post you'll know i am having an oil pressure problem.

[J Phillies]

Re: Compression issue or not?

did you check to see how long they would hold pressure?

[mrd05d]

Re: Compression issue or not?

did you check to see how long they would hold pressure?

Ya each one for at least a minute or two...

[accident_prone247]

Re: Compression issue or not?

those are all decent numbers although since 3 and 5 are together and lower that means that there is a slight leak happening. although not enough to warrant to much concern but enough that i personally would change it out as soon as i could afford some down time on the car. or money permitted

[mrd05d]

Re: Compression issue or not?

those are all decent numbers although since 3 and 5 are together and lower that means that there is a slight leak happening. although not enough to warrant to much concern but enough that i personally would change it out as soon as i could afford some down time on the car. or money permitted

What do you mean leak? From head gasket you mean? Would this leak be the reason for only getting 40 psi on cold start (oil pressure) and around 15 (psi) warm. I checked the numbers with mechanical gauge and it says the same...

[cam98aro]

Re: Compression issue or not?

What do you mean leak? From head gasket you mean? Would this leak be the reason for only getting 40 psi on cold start (oil pressure) and around 15 (psi) warm. I checked the numbers with mechanical gauge and it says the same...

i would not drive that car with those oil pressure numbers

[accident_prone247]

Re: Compression issue or not?

What do you mean leak? From head gasket you mean? Would this leak be the reason for only getting 40 psi on cold start (oil pressure) and around 15 (psi) warm. I checked the numbers with mechanical gauge and it says the same...

it probably is the head gasket but the oil issue isn't related to the compression of the engine. i would venture to guess some bad bearings for the oil pressure problem. does your oil pressure change while giving it gas or does it stay at 15 once warm no matter the amount of throttle given? and driving with that little of oil pressure isn't a good idea.

[mrd05d]

Re: Compression issue or not?

it probably is the head gasket but the oil issue isn't related to the compression of the engine. i would venture to guess some bad bearings for the oil pressure problem. does your oil pressure change while giving it gas or does it stay at 15 once warm no matter the amount of throttle given? and driving with that little of oil pressure isn't a good idea.

It changes a little bit but not much when i rev it changes maybe 5 psi...

[Opontee]

Re: Compression issue or not?

did you check to see how long they would hold pressure?

The gauge holds the pressure, not the cylinder. The cylinder CREATES the pressure. Also, you need to have al the plugs out and HOLD THE THROTTLE WIDE OPEN WHEN DOING THIS.


You need to do a LEAK DOWN TEST. That will tell you where what ever is leaking is leaking from.

[Pewter02Camaro]

Re: Compression issue or not?

So i ran a compression test today on my 96 Camaro 3.8 and got these numbers. What do you think they mean...


1 - 185 PSI
2 - 185 PSI
3 - 165 PSI
4 - 185 PSI
5 - 175 PSI
6 - 185 PSI

So this is the first time ive done a compression test but since 3 and 5 are next to each other and are lower does that mean a head gasket issue?

Also If not does 3 have any issues or is everything pretty much normal for a 3.8 with 95k miles on it?

If you read my other post you'll know i am having an oil pressure problem.

those are decent numbers for a compression test. rule of thumb is that your lowest number regardless of side should be no less than ten percent lower of your highest number. you could do a leak down test if you wanted to but what your are looking at with either of these test does not have anything to do with oil psi. i suspect you have a worn oil pump or somthing to that nature, they have been known to wear to much at times.

[Richardcoelho]

Re: Compression issue or not?

wow that psi is low,my mechanical gauge says 60 psi cold then 40 psi when warm.

[Mark42]

Re: Compression issue or not?

those are decent numbers for a compression test. rule of thumb is that your lowest number regardless of side should be no less than ten percent lower of your highest number. you could do a leak down test if you wanted to but what your are looking at with either of these test does not have anything to do with oil psi. i suspect you have a worn oil pump or somthing to that nature, they have been known to wear to much at times.

I agree, this is good advice.

Also note that the compression with 3 and 5 will most likely deteriorate with time, especially if you like to hit the red line often.