i have a 98LS motor that had very low compression in 2 cylinders (like 50 or 60) It was boosted on for about 10K miles, daily 5lbs, on occassion 10lbs. factory sealed engine. I replaced the motor with a new one, and have since taken the head off the old one. I dont see any scaring of the walls, and everything looks okay. what could cause compression loss and how can I tell what the problem is without taking the pistons out?

 

Valve seals.
Piston rings.
Bent valves.
Bad headgasket.

 

how can i check for bad piston rings?

 

Pour a teaspoon of oil in through the spark plug hole before a compression check. If compression goes up, it is your rings.

 

can i still do a compression test with the engine out of the car?

 

Yeah as long as it is mounted properly.

 

Damn spade, everything I was about to say, you said. Oh well.

 

I've been around too long....

 

any other ideas?

 

ok here is what you do Take the enginge out of you garage put it in the trash can like you did with my tranny and buy a new bumper for the eg asshat