cold leakdown test=bad readings?
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From: mansfield ohio
Help/opinions on my leakdown test I did a leakdown test on my engine while I was waiting for my new pushrods. I did the test with the rockers off and a cold engine. I got between 19 and 21% across the board 
while i know thats high im wondering if anybody has done the test with a hot and a cold engine and how much less the leakdown will be when its hot. It will be at least another week untill i can start the car again. I have known from the start with this engine that there was an issue with blowby. It was pushing oil into the intake. I tried the ls6 valley cover the catch can then i realized it was pushing the oil into the intake through the line off of the valvecover thats supposed to be the inlet for fresh air into the engine. even at idle the pcv doesn draw enough air to keep the crankcase at a negitive pressure. I then went to the breather on the valve covers which solved my oil in the intake but oil would come out and fall on my headers. So i ran a hose to the breathers away from the headers so hopefully it wont smoke after every pass from the oil on the headers 
while i know thats high im wondering if anybody has done the test with a hot and a cold engine and how much less the leakdown will be when its hot. It will be at least another week untill i can start the car again. I have known from the start with this engine that there was an issue with blowby. It was pushing oil into the intake. I tried the ls6 valley cover the catch can then i realized it was pushing the oil into the intake through the line off of the valvecover thats supposed to be the inlet for fresh air into the engine. even at idle the pcv doesn draw enough air to keep the crankcase at a negitive pressure. I then went to the breather on the valve covers which solved my oil in the intake but oil would come out and fall on my headers. So i ran a hose to the breathers away from the headers so hopefully it wont smoke after every pass from the oil on the headers Last edited by koolrayz; Mar 11, 2006 at 08:54 AM.
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From: Portland Oregon
I leak tested my stock LS1 from a 99 C5 when it was cold and it was 3 or 4% on all cyls. My race motor with more ring end gap was 5-6% after break in. If you are doing the test right, and your gauge is accurate. I'd say that your motor is worn out.
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From: mansfield ohio
Its a brand new tester. Im sure the readings are right. It would explain the high crank case pressure. What sucks is this engine has less than 4,000 miles on it and has had the symptoms of high crank case pressure since it was new. I called and talked to the builder last week and he told me to take the readings again warm and it would go down to 10% and that would be OK 
I say thats bullshit it wont go down that much and 10% is to high.
I say thats bullshit it wont go down that much and 10% is to high. Thread Starter
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From: mansfield ohio
hasnt blown the dipstick out yet. I think it was a setup issue with the rings from the builder. I had the ohio boys do the engine install for me they did the startup and seated the rings. they are no strangers to high performance engines. swapping the engine was to much to do alone on jackstands. They do great work at very resonable prices.
Originally Posted by koolrayz
hasnt blown the dipstick out yet. I think it was a setup issue with the rings from the builder. I had the ohio boys do the engine install for me they did the startup and seated the rings. they are no strangers to high performance engines. swapping the engine was to much to do alone on jackstands. They do great work at very resonable prices.
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I believe a method of determining if it's actually your rings is to squirt a bit of oil in each cylinder. Supposedly if the % lowers than there's a better chance it's your rings at fault.
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From: 8000DA Land
i know this is kinda "old" but i did a cold test on my car yesterday after spinning the stock engine to 8000rpm..
4 pistons were showing 9%, and other 4 were at 20%.. I indeed was sad.. Then, after playing with piston position a bit.. all cylinders were cool at 9%...
4 pistons were showing 9%, and other 4 were at 20%.. I indeed was sad.. Then, after playing with piston position a bit.. all cylinders were cool at 9%...
