Diagnosing a head gasket
07-31-2009, 09:51 PM
#16
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Year: 2001
Model: Cherokee
Engine: 4.0
I am curious about his diagnosis, if the gasket between those two cylinders were leaking then those two cylinders would have pretty much the same exact reading and most likely a lot lower than 120 and 140. Reason being is that all plugs should be removed and then each cylinder tested. So if you have a gasket leak in between those two cyinders with no spark plugs in any of the holes compression should be pretty low because it wouldn't hold that much pressure and escape to the neighboring cylinder that the gasket is blown between... You may trust your mechanic but in this time where the economy is bad it would not hurt to get a second opinion... especially on a decent size job like that...besides a compression test what other test did he do. Did he do a combustion test with a block check type bulb tester and the blue fluid that changes to yellow in the presence of combustion? Again second opinions wouldn't hurt. It also keeps mechanics in check....
08-01-2009, 11:49 AM
#17
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Join Date: Mar 2009
Location: Griffin, G.A.
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Year: 1990
Model: Comanche
Engine: 4.0 I6
I am curious about his diagnosis, if the gasket between those two cylinders were leaking then those two cylinders would have pretty much the same exact reading and most likely a lot lower than 120 and 140. Reason being is that all plugs should be removed and then each cylinder tested. So if you have a gasket leak in between those two cyinders with no spark plugs in any of the holes compression should be pretty low because it wouldn't hold that much pressure and escape to the neighboring cylinder that the gasket is blown between... You may trust your mechanic but in this time where the economy is bad it would not hurt to get a second opinion... especially on a decent size job like that...besides a compression test what other test did he do. Did he do a combustion test with a block check type bulb tester and the blue fluid that changes to yellow in the presence of combustion? Again second opinions wouldn't hurt. It also keeps mechanics in check....
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