New water pump, new stat still overheats

[littlecobra]

I have a 94 Cherokee that overheats. I've had a problem where after I check upon overheating and the upper radiator hose is only partially hot, which meant that water was not circulating. So I changed out the thermostat and the water pump but same problem. Also, due to the overheating, my head gasket blew and I tried using block weld through my radiator, that could also contribute to the problem. Anyways, right now I'm attempting to clean out the radiator as a clogged radiator is my only option left. Would anyone know what the problem is and if I should change out the radiator also?

[BCBlues]

Sounds like you need to do a head gasket, unless you already have done that.

Back flush heck out of the cooling system to get all of that block weld stuff out. Use a cooling system flush additive and follow the directions.

Replace that 10 year old radiator with a new one.

Replace the fan clutch. This is the most forgotton cooling system part. when they get old they still turn the fan so the clutch looks like its working. But if it is not working properly your fan will not be turning at the same speed as your engine, and will not move enough air to cool the radiator. They are not to expensive and are easy to change, when the radiator is out.

[Rmatney]

I have the same problem.... Changed the radiator, water pump, fan clutch, Hoses and thermastat.... Still overheats. One thing I noticed is that after I replaced the electric fan that when it is running hot that only the top 4 inches of the radiator was hot the bottom 3/4 of the radiator is cool to the touch. I have read that this is caused by lack of turbulance in the water entering the radiator allowing the water to channel through the top wasting 3/4 of the thermal transfer area. This appears to be what is happening to mine. If this was an old radiator I would suspect that the bottom is plugged but I have run water through it with the lower hose removed and it flows well. The one reference I have found points to re-manufactured water pumps that do not produce enough flow to cause the necessary flow disturbance... Has anyone else notice this with their overheating problem... remove the electric fan and let the engine heatup and when the temp climbs touch the bottom of the radiator and see if it is cold...

I guess I will try a high flow water pump and see if that helps...

Ron

[dna fab]

have your heater core and rad flushed also make sure you check for air locks in the cooling system you mite have 2 fans ? make sure they are both functional and in proper working order

[gtmud]

My 00 XJ had a simular heating problem. Found out ENTIRE system was clogged. Replaced everything(W/P,T-stat,RAD,HTRCR,hoses) Check your hoses for a rust like build-up, if you find it good chance that your system is probably clogged and no matter how much flushing you do, it will still over heat. I know, I tryied everything known to man before I found the clogged items .

[Saudade]

Originally Posted by Rmatney

I have the same problem.... <snip>
Ron

I had similar problems with my '88. Since the cooling system is a closed system (everything under pressure), it's a real bear to ensure it's full. I had to fill the bottle to the mark, then run the engine at high RPM's to pump in coolant and purge out some air. Then let it cool, add more coolant and run it again, and again, and again, until I saw coolant flow back into the bottle even at idle. Once I kew the coolant level was right, the electric fan kicked in when it was supposed to and the needle never climbs as high as it used to.

Make sure you get a new cap for the expansion bottle. Turns out it was the culprit on mine.