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89XJ overheating Baaaaaad ! !

sassyspapa

NAXJA Forum User
Location
Minnesota
I've come to you guys before and have always had good luck so here goes. I've changed all the hoses. I've changed the radiator. I changed the bottle. I changed the water pump. I changed the thermostat several times. The entire cooling system has been replaced. I have flushed the engine block with high-pressure hose. Check capacity of the engine block to hold fluid it seems to be holding just about exactly what it should be I can't think that there's a blockage in that block.:dunno: I mean really guys what the hell?????????
 
I might also ask the question has anyone out there changed over to the newer system with the cap on the radiator? If so didn't actually do any good or was it another big waste of time not to mention money?
 
Yes I certainly believe that I have. But why don't you give me a brief explanation as to how to do it so I'm sure that I'm not doing it wrong.
 
Maybe your pressure bottle or the pressure bottle cap are leaking?

But to change to an open system.....you get rid of the pressure bottle.

Next get a "T" fitting for the upper radiator hose that can accept a regular "open system" radiator cap. Or forget this entirely and just replace your radiator with an open system radiator.

Then get an overflow tank that isn't pressurized. This is where the expanding coolant will flow as the vehicle get up to engine temp.
 
I changed my '90 to open, used a GDI 3 core, a 92, and added the 92 heater valve.

Pros and cons - it runs cooler, when it does. When it doesn't, it overheated until I added water wetter. It was very erratic about overheating, I could never pinpoint it until recently when I went through a dozen threads on the subject. I'm working on it.

I would say that your still fighting an air bubble or a bad t-stat. The rad cap is lower than the heater hoses, so I'd park it uphill to help it purge and recover coolant on cool down. Stats need the hole at 12 o'clock to purge, another at 6 helps even more. The recovery tank must be half full and that line purged to the rad neck, which should be filled to the max. The correct cap must be installed - don't trust yourself or the parts house, with this kind of thing OEM has a higher percentage of being right.

With all that, older Jeeps develop corrosion in the radiators that restrict flow which is the primary cause, and corrosion in the block, which is probably the one that gets us. Flushing with "high pressure" does nothing, it's chemical corrosion eaters that remove the problem (unless you were using an 1100 psi spray in the cylinder jackets and blew the hoses off the water pump.)

Beyond that, small head gasket leaks will do exactly the same - overheat - until the gasket finally makes the big exit. Check cylinder pressures and find the one or pair that are 20-40 psi lower, you might have that problem . . .
 
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Ah, you must have edited out the part about the radiator cap. The email I got for your thread response was different :)

Anyway for the open system, the correct cap is 16#. The pressure release lever/valve on some certain rad caps has nothing to do with normal operation. It is just there incase you need to depressurize the system quickly without removing the cap and getting hot coolant all over yourself. I use a 16# Stant pressure release lever type cap.
 
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