NWAE Cobalt

iTrader: (1)

most of you have seen my troubles in my buiild thread...
but tonight im going to pick up a compression tester at schucks (only 25$) and test the car to make sure im building compression...what should i be looking for as far as readings?? whats normal?
anything i need to know special about our cars before i go do this tonight?

Jn2

iTrader: (1)

crap i dont remember, all i know is they should all be around the same #

boostedss26

What year is your car? i can look on alldata

All alldata says is no cylinder reading should be less than 689kpa or 100 psi

NWAE Cobalt

iTrader: (1)

cool cool, its an 06 ls

so if its below 100psi then i have a leak...?

Sentry

I thought all cylinders should be around 130-150 psi. Just from what I remember, could be off a little though.

boostedss26

ok i looked up an 06. You don't want any more than 25 psi difference between cylinders though if i remember correctly

NWAE Cobalt

iTrader: (1)

ok, cool cool, will check tonight and post some results

NWAE Cobalt

iTrader: (1)

never posted results lol, then went out of town haha
its at 0psi...
pulling the head and checking for bent valves this week

~Mike~

iTrader: (2)

Dumb question cuz I've never had to do it or known someone that has, but how do you check compression? I think I might have a problem, but I don't wanna take it to the dealer and have it gone for a week or however long they think they need to make me wait

NWAE Cobalt

iTrader: (1)

you buy a tester (mine was 30$ at schucks), pull a spark plug, instert the tester, pull the fuel injector fuse so you dont get fuel, and turn it over 3-5 times and read the compression, do this to all cyl and check the numb, all 2.2l i have done show between 170-190psi...and i think they are supposed to be within 15psi of each other. if it shows low, then drop a few drops oil and try again, if that fixes it then you have worn rings or cyl walls. if it doesnt then head gasket or valve problems

~Mike~

iTrader: (2)

well mines a 2.0, not 2.2 so i don't know if my compression numbers would be the same, but I'll check into that tomo since I have the day off. Thanks for the info...I keep smellin antifreeze from my exhaust, so i hope this helps me track down the issue

NWAE Cobalt

iTrader: (1)

from what im told, that sounds like a head gasket issue

Nighthawk243

It may also be a leaking line putting coolant on the exhaust manifold. I think the thermostat housing is toward the back.

~Mike~

iTrader: (2)

Honestly, that's what I'm hoping. It's alooooot easier than replacing piston rings or valvetrain components. But, can't hurt to double check my compression and make sure. If i do a head gasket myself and have to take it back to the dealer later for something, are they gonna know? and would it void out my warranty?

NWAE Cobalt

iTrader: (1)

would they know?? i suppose they might if you use diff bolts (aftermarket not gm head bolts) or a none gm head gasket...and if they did im sure it would void the warranty

Nighthawk243

Just use GM parts... you should be able to order the bolt set and gaskets off of crate engine depot or GMPD or something.

PSHHH

or just dont do any lower block damage next time you take it to them so they never get to the gasket

Red07SSNA

To do a proper compression test you have to remove all the spark plugs, disable the ignition and fuel system, insert the compression gauge in one spark plug hole at a time, and crank the engine at least 4 cycles each test. Having all the spark plugs out allows the starter to crank the engine for the test -- it doesn't have to "fight" the non-tested cylinder's compression during the test.