99 cherokee overheating problem solved now low compression
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Joined: May 2010
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From: Shanksville pa
Year: 1999
Model: Cherokee
Engine: 4.0
OK after doing some investigation work I found why my jeep was overheating I took off the water pump and there were no blades left on the pump and it was packed full of rusty sludge. My new problem is when I was doing my investigation "looking for a blown gasket" I found that my #1 cylinder only has 50 lbs of pressure so I put oil in the cylinder and the PSI went right up to 140. cylinders 2-6 were all in the 130 to 140 range which I think is OK. my question is should I only address this one cylinder or should I overhaul the entire engine. before it overheated it seemed to run ok but when it overheated the engine was making quite the racket. I let the engine cool off and it started and sounded fine.
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Joined: Mar 2010
Posts: 8,135
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From: Gilbert AZ/Las Cruces NM
Year: 1996
Model: Cherokee
Engine: 4.0 upgraded
I would still take the head off, make sure it is not warped, if so have it planed down level again and replace the head gasket.
It will be a good days work and here it is $100 have a head planed level again.
It will be a good days work and here it is $100 have a head planed level again.
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Joined: Dec 2009
Posts: 224
Likes: 1
From: Southern California
Year: 1988
Model: Cherokee
Engine: 4.0
OK after doing some investigation work I found why my jeep was overheating I took off the water pump and there were no blades left on the pump and it was packed full of rusty sludge. My new problem is when I was doing my investigation "looking for a blown gasket" I found that my #1 cylinder only has 50 lbs of pressure so I put oil in the cylinder and the PSI went right up to 140. cylinders 2-6 were all in the 130 to 140 range which I think is OK. my question is should I only address this one cylinder or should I overhaul the entire engine. before it overheated it seemed to run ok but when it overheated the engine was making quite the racket. I let the engine cool off and it started and sounded fine.
Tough to answer this as if the compression in the no. 1 cylinder goes up after adding a little motor oil usually means that the rings are worn. If you re-due the head it should not help the compression issue. If you decide to re-ring the cylinder you should go ahead and do the other 5 also. I do not know what to tell you! Good Luck!
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Joined: Mar 2010
Posts: 8,135
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From: Gilbert AZ/Las Cruces NM
Year: 1996
Model: Cherokee
Engine: 4.0 upgraded
actually!!!!! just remembered !!!!! do a leak test see what is leaking on number 1 cylinder to give you that little compression, open your rad cap to look for bubbles while you do it and also listen in the exhaust pipe to see if an exhaust valve is blown giving you low compression
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