Compression test results

[frosh29]

What's up everybody,

I recently bought a 1991 GSX from a guy really cheap. The motor is running, but I am not sure how many miles are on the rebuild or if the motor was really even rebuilt with what he said was in it (Wiseco + manley's)...

Here is what I bought the car with: 1991 Eclipse GSX, Hunter green. Springs/KYB AGX's. Stock motor/trans. Came with a blown 16g and an HKS VPC! Full exhaust. Clean inside and out. ODO says 160,xxx. COST: $1000

Anyway, I cracked the hood open tonight and started the motor up to get it to temp for the compression test. Started right up, let it run up to temp. Pulled the coil plug out, and started the compression test.

First cylinder...60 - A poor start, but nothing I wasn't expecting to see, knowing nothing about the car.

Second...120
Third......120
Fourth....120

All in all, not sure why #1 would be so bad. Anyone have any info they would like to ad taking into account the results and the description of the car? I am going to rebuild it anyway, that was in mind when I bought the car. I was just wondering what you guys thought.

Thanks.

 

[jwahl16]

Try doing a wet compression test after to see if any of the numbers increase. That will narrow it down some.

 

[Tanro]

+1 to wet test. If you have not done one before poor a cap of oil down the spark plug hole and repeat the compression test for cylinder 1.

 

[frosh29]

Hey,

Sorry, I didn't put that in the original post. Wet tested the cylinder, went from 60 to 70.

Thanks,
Scott

 

[bwhite]

Is the engine running rough?

 

[Tanro]

Sounds like a bad head gasket or bent valves to me rather than bad rings. I would have the head pressure tested and purchase a new headgasket.

If the valves are bent you can probably just have those 4 valves redone.

 

[frosh29]

The engine is running alright to be honest. The kid changed out the turbo, and did not connect the o2 housing and the downpipe, so there is a huge exhaust leak... I didn't think that this would affect the compression of the cylinders.

When I rev the motor, it sounds strong, doesn't vibrate too much. I've heard a lot of these engines, this one does not sound bad for having such a poor result in the cylinder.

Either way, the numbers don't lie... I will just verify the internals, decide if I want a different setup, and rebuild. Prob Wiseco/eagle.

I'll update this thread when I tear it out of the car and open the block..

-Thanks,
Scott