This might have been discussed somewhere else, but a quick search didn't pull anything up.

I did a compression test today and pulled the following numbers from left to right.

125
130
155
150

I'm trying to find a frame of reference to compare to. What are your numbers?

 

oh noesssssss.

 

Game over. All numbers should be within 3 psi of each other.

 

correction 30 ^

 

I somehow doubt that. I think two of them are a bit low, granted, but they don't have to be that close.

 

A quick search revels 10-15 psi at max difference is acceptable.

Looks like some weak cylinders.

 

something is going on there....normal compression numbers are not that far off.


but I`m also used to seeing one cyl being way off the others. you might be ok.

 

Try a wet compression test.

 

I'd be more suspect of a bent valve than a piston issue. I am going to check the valves later tonight.

If it does happen to be a bent valve or a piston ring, I'm going forged, as much as I didn't want to.

 

You might need a rebuild soon

 

Why does bent valve = forged internals?

 

Because it means I'm going to have to open her up anyways, might as well drop in some forged pistons and rods and let her rip. I bought a little POS hatchback so I wouldn't have to do this to the DD, but it looks like I'm going to have to.

Mechanic will give me the diagnosis Tuesday.

 

To find out if it is valves all you have to do is check for air leaks when cranking it over by hand(listen at the exhaust and throttle body)

 

To check for bent valves do a leak down test.

 

You mentioned you flooded the cylinders right? Read my pm, i bet it will bring your compression numbers closer together...

Basically poor a little oil down into 1 and 2, turn her over without the boots on, then start her up and burn the oil out then redo your test. Drive the car for a bit and do another test. You should bring those to cyl's back up closer to the others.

 

Minimum spec is 100, 150+ is much better. Maximum deviation is 30% from high to low, 20% is a better target. Squirt some oil in the cylinder and rerun the tests, if the compression improves to closer to other cylinder then youve got a ring/piston/cylinder wall issue, if it doesnt its most likely valve related.

 

So what are avg numbers you would see from a 2.2 ecotec? Should healthy motors be pulling ~150s across the board?

I may have misread but im pretty sure there was a turbo lsj guy pulling 190s and thats on 9.5:1 compression so shouldnt we pull higher #s?