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compression test

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Old 06-21-2012, 08:03 AM
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Default compression test

So yesterday I did a compression test and these are the results


1-180
2-180
3-180
4-180
5-180
6-30
7-175
8-180
It's a fresh rebuilt 5.7 with cheatr cam and 7.4 pushrods u with compression being so dam low on 6 does that seem like a bent valve
Old 06-21-2012, 08:14 AM
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If you had a bent valve most likely you would have 0 compression. Could be a bent pushrod, allowing but to only open alittle bit. I'd take the rockers off and check those first.
Old 06-21-2012, 08:29 AM
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K I will check I forgot to mention that the spark plug was coverd in oil
Old 06-21-2012, 09:30 AM
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Could be a number of factors (probably not a bent pushrod though). Valve burnt or debris sticking the valve open, worn rings, broken ring, broken ring landing, hole in the piston, etc. I would run another compression check on #6 cylinder to be sure. If it is still bad, you'll probably have to pull the head to see what the problem might be.
Old 06-21-2012, 09:43 AM
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Start calling friends and neighbours to find a bore scope so you csn look down in there and try see anything wrong.
Old 06-21-2012, 11:13 AM
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I might have to pull the heads and see
Old 06-21-2012, 11:15 AM
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If a valve would of hit the piston would I have herd somthing
Old 06-21-2012, 01:08 PM
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Maybe, maybe not. If this happened at WOT and you have loud exhaust, then you could have easily had contact and not known it. If you suspect a valve hitting the piston, pull the rocker cover off and inspect the valve springs on that cylinder to see if anything broke.
Old 06-21-2012, 02:08 PM
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K na I'm tuning stock exhaust all the way back since the cheatr cam said it worked well with stock headers soon as I get out of work Imma. Go and check I called autozone and oreilly and ask for a leakdwn loaner they don't know what that is lol
Old 06-21-2012, 02:42 PM
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Do some research on how to do a wet or a dry compression test to determine if it is a piston & rings problem or if the problem is in the head.
Old 06-21-2012, 07:35 PM
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Fix the problem thanks so much everyone the crazy thing happen the rocker ARM cam of the pushrod and was hanging at the tip of the spring with pressure pushing on the pushrod had the valve open a small amount I got lucky sound like a champ now



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