Mechanics

CHEVY COMPRESSION PROBLEM

1999 Chevrolet Tahoe

Engine Performance problem
1999 Chevy Tahoe V8 Four Wheel Drive Automatic 114000 miles

I have low compression in cylinder #4. How do I correct this problem? Are there any quick fix solutions to resolve this? Lucas type products or engine restore products? Will I have to replace the piston rings? Any idea on a cost to repair the issue?
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Tx.hittman
February 28, 2010.



Hello tx. Hittman

You need to isolate the problem to the valves or rings by squirting a little 30 weight motor oil into the cylinder(#4) through the spark plug hole and repeating the compression test. The oil temporarily seals the rings. If the compression readings is higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings would tell you the cylinder has a bad valve.
A Further leak down test will pinpoint which valve is leaking.
Remove #4 spark plug. The crankshaft should be turned so that #4 piston is at top dead center
(both valves closed) when the cylinder is tested.
A threaded coupling attached to a leakage gauge is screwed into a spark plug hole. Compressed air (80 to 90 psi) is then fed into the cylinder.
If you hear air coming out of the tailpipe, it indicates a leaky exhaust valve. Air coming out of the throttle body would point to a leaky intake valve. Air coming out of the breather vent or PCV valve fitting would tell you the rings and/or cylinders are worn.
A leaking valve need to be replaced so is piston rings.
Engine restore product are not guaranty to solve problem such as worn valve seal or worn cylinder rings.
Call at least 4 to 5 shops around where you live to compare prices

Tiny
Mathiaso
Feb 28, 2010.