1999 Chevy Tahoe 99 tahoe low compression on #4 cyl

Hello,

Ok, next step...

Do another compression check on the #4 cylinder and right it down then sqirt a little oil into the cylinder and check compression again.

If compression increases then you have bad rings.

If compression remains the same then there is a problem with the Valves or possibly the head gasket.

Also what did the plug look like when you pulled it?


Mark S


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OK..I tried it again a couple more times today...Same result. I am not losing any coolant and no oil in the coolant..I guess the heads gotta come off now ?? Or is there anything I could "try" to bandaid it with?

Ok, so wet test results were same as dry. right?

If so then there are a couple possibilities...

One is the valve spring has failed and compressed so the valve isn't closing all the way. this you can check by taking the valve cover off and using a tale measure a small narrow one you can measure and get a rough height on the the #4 cylinder springs, then the others and compare.

Another cause could be build up on the valve. You can remove the exhaust manifold and look at the valves to see if the are closed completely or not.

If a valve has broken a small piece off then you may not see that till head comes off.

One other thing, have you noticed an increase in radiator pressure or it sounding like it is boiling over into the overflow tank.

I have see this more on fords than chevy. But, the head gasket blows between the cylinder and a coolant port and this shows no oil in coolant nor coolant in oil, but does push exhaust though coolant system. You can check by starting vehicle and opening coolant overflow tank if it is bubbling and has an oder of exhaust then you do have a blown head gasket.

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