Compressed Air + Cylinder = Pop! No Compression

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Nov 26, 2006 | 09:09 PM

FastJeep4X4

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Compressed Air + Cylinder = Pop! No Compression

My brother and I are doing a valve spring swap on an engine outside of the car, and used the air compressor method to hold the valves up. It worked well on all cylinders, but cylinder 1 we did last, we used less than 80PSI. All that I can think of is the valve was leaking and build up pressure since we had a long pause before doing that cylinder last. We heard a loud pop, and air leaks out nonstop into the engine somewhere. What could have happened so we have an idea how bad we are screwed. Thanks

Nov 26, 2006 | 09:15 PM

Rhino79

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From: Cabot, AR

Ring maybe?

Nov 26, 2006 | 09:15 PM

calongo_SS

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From: Victoria, TX

80 psi is no where near enough pressure to damage anything in the cylinder or combustion chamber. maybe there is a bent valve on that cylinder, see if you can tell if the air is coming out the intake, or going into the exhaust. if it's not going in one of those places it's got to be going past the rings.

Nov 26, 2006 | 09:19 PM

FastJeep4X4

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Wait a sec, the front cover is off.... Is that the problem? We completely forgot it was off, since we need locktite for the bolts under it... Thanks for help guys

Nov 26, 2006 | 09:20 PM

blkbird

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From: san antonio, tx

Are you sure the valve didnt just open up while compressing the spring? I had that happen to me a couple of times...

Nov 26, 2006 | 09:36 PM

Ferocity02

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The front cover has nothing to do with it. The cylinder should hold compression no matter what. The crankcase doesn't hold pressure. In fact, if you put more than a few psi in the crankcase you'll blow out some of the gaskets.

Nov 26, 2006 | 11:00 PM

FastJeep4X4

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Quote:

Originally Posted by blkbird

Are you sure the valve didnt just open up while compressing the spring? I had that happen to me a couple of times...

You where right! we put the compressor on it and lowered it with TCD method and swapped spring and put it back and checked with air pressure to see and it had to have been open a little, no air escaped. Thanks blkbird