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Dr. Hamman
Dr. Hamman, Technician
Category: Classic Car
Satisfied Customers: 6286
Experience:  I have 30 years experience repairing, restoring, and customizing cars, and pickup trucks.
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Jeep CJ3: 1949 CJ3A overheats just idling . Water pump was

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1949 CJ3A overheats just idling . Water pump was leaking so replaced it and thermastat now it over heats

DR. Hamman :

Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time.





Sometimes these get real hot waiting for the thermostat to open when you have had them apart, because of air and steam pockets that form. Once it gets past this and the thermostat opens and you top it off a few times then it should settle down. Do you think you are past that with all the air purged out of the system. If it is full of water and the thermostat has opened we might have to dig deeper. Let me know.

Customer:

It's my brothers jeep and he's the mechanic but he's in S . Korea . It has boiled over many times and we refilled to get it home . It does seem to cycle the coolant but slowly till it's already hot .

DR. Hamman :

OK, them you are past the time when the pocket of air could be the problem. Was it overheating before the pump, and thermostat replacement.

Customer:

No and we lived in Texas then and used it in 100 degree weather .

DR. Hamman :

I's in Texas too, hot today. I would suspect that the thermostat might be bad. I have installed a lot of them through the years that had problems. The best way to confirm this is to either pull it out and then put it back together without a thermostat, and run it. Or you can put it in a pan of water on the stove and it should open up before the water boils. You can actually see it open. That would be the first thing I would o. The water pump on these cant be installed wrong. I believe the gasket doesnt have any water passages that can be blocked, and the gasket cant be installed wrong, it either goes on or not.

DR. Hamman :

Sorry about the I's it should have been I'm

Customer:

Ok , thanks . this one in now is the third one I've tried but I didn't test it before I put it in , I'll give it a try !

DR. Hamman :

Third one, wow. you might try it without a thermostat to see if it still overheats. Sometimes these little engines get a pinhole leak in the head gasket that can make them overheat when everything else is great. There is a tester you can check for this problem with. What you do is to check for combustion has in the cooling system. When this happens sometimes the only symptom is unexplained overheating. I will post a link HERE where you can get one of these tools, you can probably find one locally too. You take the radiator cap off, and put it in the top of the radiator to test it. Let me know if you need any more help, good luck with it, and thanks form using Just Answer.

Customer:

Thank you Sir !

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