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Discussion Starter · #1 ·
I lost 2/3 of the compression in the 4th hole. It has spark and there is a little noise coming from the top of the motor at idle, it goes away if I rev it up. I am about ready to take the cam girdle off-any suggestions or previous experience? Broken v spring, retainer?
 

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Re: Lost compression in 4th cylilider @99K (racedoc)

Have a cylinder leak-down test performed first. That process is to run the engine until it is warm, then pressurize each cylinder in sequence. Cylinder must be at TDC. Then you check your gauge to see what percentage it is reporting. Anything less than 10% leakage you ignore on a street engine. If you have leakage in a cylinder, your #4, then you listen at the tailpipe for exhaust valve, at the intake for an intake valve, at the oil cap for rings. <p>Don't guess, find out what it is before taking it apart and finding out that it is a broken ring, not a bad valve.
 

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Discussion Starter · #3 ·
I am afraid to run the engine to warm it in the event it is a broken retainer OR valve spring. I dont want to help it break the valve stem and go into the piston.
 

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Re: (racedoc)

Hmmm, might be able to do leak-down test of sorts with a cold engine. Even though it won't be a valid test of the rings, it might tell you which valve(s) leak.
 
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