Oh hey! I'm new here. What better place to learn and seek advice. I'm definately no mechanic, pretty novice.. But I know the basics. Anyway, here's my current situation. My Jeep is overheating badly at idle. Just replaced the upper and lower radiator hoses, but am still periodically leaking small amounts of coolant. Thermostat tested good, pressure test was good. I rarely hear the cooling fan kick on so I'm guessing a bad relay there. But inconsistently leaking fluid?

I have a regular trustworthy mechanic, but I had to have it towed to another local shop when the upper hose blew on me. Guy says "Oh it must be a bad head, has 190k miles." I questioned the water pump, bad cooling fan, the whole radiator. He still insisted blown head. Love being a female at a repair shop. Any thoughts guys? She runs fine when driving and cool air is getting in. Have another couple weeks before I can take her in. Ideas???

 

Welcome to CF!

I would try hot-wiring the cooling fan to run whenever the ignition is on and see if it still overheats. If it doesn't, I'd say the relay is at fault. The '99-'01 4.0s have a reputation for cracked heads, but they usually crack into the waterjacket between the #3 and #4 cylinders and leak coolant either into the exhaust or valve area, not into the cylinders themselves. This usually results in a loss of coolant from the reservoir, steam or water from the exhaust, or coolant in the oil. I just went thru this with mine.

Take the radiator cap off when it's cold and start it up. Watch for bubbles in the radiator or put a pressure tester on it. If it starts to pressurize before it gets hot, you've probably got a blown head gasket, not a cracked head. You can also observe the cooling fan while doing this. It should start on high when it reaches 210*F and slow down after the temp drops. The fan relay is located underneath the right headlight's mounting pocket and can be accessed by cutting a "trap door" in this plastic panel OR removing the whole grill and headlight assembly.

The only other thing I can think of is the water pump. They've started using plastic impellers and if the bearings get worn, the impellers sometime shatter. If it only overheats when idling, I would think it's the fan relay. DO NOT go for a new head until it's proven that's what it is.

 

I agree with Dave. From your description it doesnt sound like a bad head or head gasket. I'm thinking the problem lies in the fan/fan relay.

I'm not sure if this works for Chrysler, (I've worked on Fords my whole life) and someone please correct me if I'm wrong, but if your a/c works you can turn it on max and your cooling fan should automatically kick on after a few seconds. If it doesnt, then there's an issue with the fan set up.

 

Drove her to work and when I parked I turned the a/c on, which I normally don't because it makes the temp jump up quicker, couldn't hear the fan. Popped the hood and the fan is definately not on.

Would that malfunction cause radiator leakage though? I've been trying to read up on how exactly the entire cooling system works and it seems like Betsy has symptoms for every issue haha.

 

those electric fan are not funny, i just replaced that thing for a fan clutch and vent from a dakota and problem solved forever, cheers!!

 

If the fan did not turn on, it is most likely the fan motor or fan relay. If you change the relay and it works for awhile then blows again, its the fan motor going bad. Had same issue on my 03 grand Cherokee. As far as the leak goes, does it do it after shutting it off? Or is the leak constant, where is the fluid coming from? Need more info. May be as dave said though, a water pump with bearings going out will cause it to leak through the weep hole in the pump.