Ok, so I had a compression test done before I went turbo, several months ago. Came up ~220 across the board, I believe the highest variance between cylinders was like 4psi.

Recently after going turbo I've been having CRAZY overheating problems. Doesn't get hot on the way to work in the morning, but in the afternoon or anytime its really hot outside it gets up to like 3/4 to 5/6 up the stock gauge and fluctuates-- goes back down randomly then increases again when I get on the throttle. And if I turn on the heater it drops way down to between 1/3 and 1/2 which is normal from when I was nonturbo. I won't go into all that in detail but there are a few threads on 2gnt I've started detailing it. I suspected the headgasket may be gone. Btw, the car was smoking a little but isn't at all anymore.. it was blowing a bunch of smoke at WOT only the first time I did a WOT pull each day for a few days. After doing the wet compression test today, the same smoke came out, so I must have been burning some oil.

Anyhow here are my results. Both tests were done with the engine hot (operating temp, after driving for about 20 minutes.. and yes, it did start getting to about 3/4 up the gauge).

First test: 198, 182*, 190, 195
*-- on the #2 cylinder, the first crank didn't make the gauge JUMP, it took a bit longer to build the pressure unlike the other 3 cylinders

Wet test (1.5 capfuls of oil per cylinder): 265, 235, 230, 225

A couple things worry me..

1. #1 cylinder was always higher than the others, is that ok and why would that happen?

2. Like I mentioned above, the #2 cylinder built pressure more slowly, so I'm fearing the rings may be worn on that one for some reason.

3. All the compression numbers were significantly better on the wet test, which leads me to believe I may HAVE blown the HG or all the rings need to be replaced.

Help! What do you recommend, and what do you think these results mean?

 

i recommend NOT turbo-ing a 420a

u put oil in the cylinders and the psi comes up,the rings are burnt

#2 MAY have a small hole in the piston,or the piston has become porous

i would say,at least,pull the head off,and see what u got going on,you're most likely lookin at a rebuild

 

over heating + low compression = head gasket . imo putting oil on your piston is not a great test its old and out dated ..i would find some one with a leak down tester and you will stop guessing. i have one im in new port richy .

 

you don't put "small" holes in pistons without serious problems....

Headgasket, pull the head and goto town.

 

From personal experience, when you disassemble your engine, you're going to find that you've killed the ringlands on the #2 piston. I'd put money on it. Our pistons are VERY brittle. Your setup is the same as my first 420a-T. And you're having the exact same problems I did.

Also, I'd say with 95% certainty, you've also popped the head-gasket.

In any case, you're looking at a full rebuild. That said, if you don't want to pull all the turbo components right away, remove the wastegate actuator, that'll keep you from building any boost. That should keep you from doing anymore serious damage to piston #2.

Now, it would be prudent to park the car until you can do a rebuild, as since you've destroyed a piston. If pieces of the piston come loose, you'll be looking for a new block, as well; You can only bore a cylinder wall so far. (Again, speaking from experience, here.)

 

if he still has that much compression his pistons are most likely still in one piece. probably just rings and/or head gasket.

 

You'd be surprised. I cracked all the ringlands on one of my pistons and it still got 185 in that cylinder. In any case, there's only one way to know for sure.

 

Fuck.

Maybe I'll buy that built block from the guy on 2gnt for a grand.

 

either way the motor needs to come apart.