Overheating

1989 JEEP PIONEER
275,124 MILES • 4.0L • 6 CYL • 4WD • AUTOMATIC
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FIREWOODFLARES
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This vehicle keeps overheating and losing fluid out of the reserve. So far I have replaced the fan clutch, the radiator, the thermostat, and the water pump. It is still leaking fluid and over heating. Usually within three or four miles. Do you have any ideas?
Aug 4, 2018 at 1:45 PM
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ASEMASTER6371
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Good afternoon.

First, did you pressure test the cooling system to find the remaining leak?

I am very concerned that you may have a failed head gasket causing it to overheat. In order to confirm, you need to do a leak down test on all the cylinders to see if it moves coolant in the radiator. You remove the plugs and insert shop air into the cylinder and watch for any movement in the coolant. If there is, you have compression leaking into the cooling system super heating the coolant and creating way too much pressure.

Roy

https://www.2carpros.com/articles/engine-overheating-or-running-hot
Aug 4, 2018 at 1:50 PM
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FIREWOODFLARES
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I have not tried that. I am not seeing any water in the oil. I did replace the valve cover gasket at the same time. I also bypassed the heater core and it ran cooler. Do you still recommend the pressure test?
Aug 4, 2018 at 2:10 PM
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ASEMASTER6371
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Absolutely. It is a real possibility that the head gasket has failed.

Roy
Aug 4, 2018 at 2:12 PM
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FIREWOODFLARES
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I will try that next, and let you know. Thanks
Aug 4, 2018 at 2:18 PM
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ASEMASTER6371
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You are welcome. Feel free to ask any follow-up questions anytime.

Roy
Aug 4, 2018 at 2:22 PM