Good/Bad Compression test

[david9291]

So I'm replacing the engine in my brother's esi with one from pick and pull cause the original has a serious knock to it, but before putting it in I did a compression test and got 160-180-150-60 on cylinders 1-4. After that I tried a wet test on cylinder 4 and got 180. To have a comparison I wet tested cylinder 2 at 300 (may have used to much oil so it is sitting in the chamber). So my question is whether this indicates bad rings in cylinder 4 or something else like valves or head gasket.

 

[96 420a-t]

Bad rings I believe.

 

[fourgsixthree33]

Might be rings. Did the car the engine came from at the pick n pull have a sticker on it? I know alot of pick n pulls have stickers that have a list of things with check boxes next to it. For example "engine". If engine is checked, that's one of the reasons it doesn't run/drive and is in the junk yard.

 

[david9291]

No stickers that I was aware of, the guy at check out had said to my brother that he had wanted to get that engine cause he new it was running, but that doesn't say much since the one we pulled ran but knocked. After reading other posts and 96 420a-t reply we have chosen to put in new rings.

 

[96 420a-t]

While you got it out replace the bearings too. A strong/fresh top end will ruin a older/broke in bottom end. Parts are cheap. I got mine for 14 a piece.

It is most likely the rings because the oil will sit on them and help them seal.

 

[Calan]

How many times did you test each cylinder? A change from 60 to 180 sounds more like a problem with the test than bad rings.

Was this test done with the engine at operating temperature? I'm guessing not if it wasn't in the car yet. But if not, how did you crank it?

 

[david9291]

I bolted the starter to the plate between the engine and trans, yes the plan is to go through the whole engine. I didn't screw up the testing, I did it more than once with the same results. It took 10 or more cycles to hit the wet 180 were as cylinder 2 hit 300 in just 4 cycles. I suspected rings but wanted a second opinion before tearing down the engine. After all this is just a rusting dented esi, but my brother likes it and has the disposable income to throw at it.

 

[dsmtunz]

could be bad rings or the lifters didnt bleed yet run the car for at least 10mins then recheck but sounds like the rings to me

 

[400hp93talon]

Can never go wrong with a rebuild while the motor is still out!