85 Jeep CJ7 overheating

I have an old CJ7 that is overheating. I tried to take it on a trip. We got about 75 miles while running great at 180 when the cooling gauge started jumping into the danger levels. I was at about 55 in 5th gear. To get it the cooling to go down to 210 (drivable), I had to shift down to 4th and drive a lot slower. When I parked it after about 20 more miles of driving that evening, It would not drive without overheating. since then I have replaced the water pump, radiator, fan, clutch, thermostat, and have removed the head and got it shaved. I have replaced all the gaskets and reassembled the engine. now when i start it and let it idle, it get up to 205 and levels off. while driving it, it gets up to 180 and holes for a little while and then goes up and overheateds. the electrical gauge is an aftermarket autometer gauge and it works perfectly.

Thanks for all the help in advance.


Why did you get the head shaved? Were you having problems with a headgasket? Warped the head?

Replaced all the gaskets? Can you be more specific? Replacing all the gaskets for an overheating problem sounds like an unusual step. Was the cooling system forcing coolant through he gaskets? Have you tested the radiator cap?

You’ve changed a lot of parts, but have you done any diagnosis? Generally if an engine is overheating at speed the fan isn’t the first place I’d look. But since you’ve changed the fan and fan clutch (which puzzles me, the condition of the fan is visually obvious, the clutch easily checked) I suppose it’s a moot point.

Have you checked for evidence of a leaky headgasket since these parts have been changed?

Have you burped the system?

After replacing the cooling system parts and the Jeep was still overheating, I got the head gasket shaved because I thought it maybe warped. When putting the head back on, I replaced the gaskets: intake, exhaust, head, valve cover and water pump gasket. No, there was no leaks in the gaskets. And the radiator cap is new-16lbs.

No, I have not checked for a leaky head gasket.

Yes, the system has been burped everytime the coolant is added.

I do know if this has anything to do with the situation at all, but I also hooked up the coolant overflow tank which was not hook up before the overheating started.

The overflow tank might be irrelevant to the problem, but it’s an integral part of the system and it’s good that you reconnected it. When the engine cools and the coolannt contracts it draws coolant back into the system from the tank. If the tank is disconnected it’ll just draw air in and you’ll develop cooling system problems. You do not want air in your cooling system.

You got the headgasket shaved? You do mean the head, don’t you?
I’m a bit concerned that you had the head shaved without first determining if it was warped or you had a blown headgasket and erosion paths, something that might justify shaving the head.

Have you changed the hoses? Hoses are made of layers, and the inner lining can collapse and restrict flow without showing any abnormal indications externally.

I congratulate you for having the courage to dive into this problem and do all this work, but at the same time I’m a bit concerned that you’re simply changing parts apparently without doing diagnosis. The head work was the clue to this.