compression issue -
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post #1 of 3 Old 07-27-2019, 05:23 PM Thread Starter
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compression issue

I have a 1991 yj the to 2.5l I bought it and it wasn't running told it needed a head gasket found that the number 1 piston had damage on the top and the rings were damaged after using a ridge reamer i removed the piston and honed the cylinder and it was okay so I cleaned the head and all of the valves replaced the piston and all of the rings put it back together and now it wont start I checked the compression wet and I have 55-60 psi on all 4 cylinders any thoughts thanks

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post #2 of 3 Old 07-27-2019, 11:17 PM
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Your compression numbers are horribly low, they should be at least twice the figures you currently have. Is your battery fully charged and cranking the engine over strongly during your checks? All plugs removed and the throttle held wide open while cranking? Is the compression tester a known good tool and sealing well?

When you say you replaced all the rings, was that only on the one piston you replaced or was it for all cylinders? If the latter, did you thoroughly clean the piston ring grooves, check your gaps, and hone all the cylinders? Are the rocker arms all torqued? Are the lifters pumping up like they should? Did you check the head and block for flatness prior to the new head gasket install?

2000 TJ SE
2005 LJ Rubicon
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post #3 of 3 Old 07-28-2019, 12:02 PM Thread Starter
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Battery fully charged all spark plugs out throttle open all rings on all pistons all grooves cleaned head and block checked I will pull the valve cover off and check the lifters if it is the gas washing the walls because of bad injectors would that cause it I don't think there is a problem with the timing any help thanks I also used my compressor to slowly apply air to cylinder 1 from 25psi to 125psi couldn't hear an air leak anywhere
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