pierre

I think my engine has been running a little hot. When im in stop and go traffic the temp creeps up towards 225. The electric fan does come on but it doesn't seem to bring the temp down that much. If I crank the heat or drive faster like on the highway the temp goes down to normal.

I wasn't low on fluid and my electric fan is working. I looked in the radiator and it looked gunked up so I flushed the system with water.

The flush didn't help. Then I noticed that the radiator had a tiny leak in it. I changed the radiator and thermostat yesterday. I still have the same problem. My upper radiator hose is hot which tells me that the coolant is flowing through it which I hope means the water pump is working

So besides the water pump what else could be going on? Or is this normal for the temp to fluctuate so much?

RTorrez1

It is normal for it to fluctuate a little. But the most common reason for it to heat up while at a stop is the fan clutch is getting weak and more then likely need to be replaced.

pierre

The clutch on the electric fan or the mechanical fan? They both operate but I guess they could be getting weak and spinning as fast?

highmileage

There is only a clutch on the mechanical fan. also do you have a fan shroud?

pierre

Yes I have the fan shroud. Is there a way I could check the clutch?

highmileage

When the engine is cold spin the mech fan and note the resistance. Then warm up your Jeep to operating temp shut it down and check the resistance. If it is noticeably more than cold it's still good, if not it is going or gone.

dougfrompa

Mine was doing the same thing. I installed a ZJ clutch fan and my water pump only had 2 of the 5 fins left due to rust. My coolant flowed thru the water pump but did not have enough flow to keep engine cool. Everything works great now. Check your water pump for rust and change the fan clutch no matter what. If it is old it is bad.

spenceoc

My 98' Cherokee had been running hot also. Whilst towing, it would reach check engine light temp.
After cooling it resumed normally and whilst going easier on the throttle it ran still very hot, but workable.
A few weeks later, the car started to stall at an idle.
I got my mechanic out to give it a scan, and it came back as a faulty coolant temp sensor. The engine wasnt running hot, the sensor was telling the computer it was. This was causing it to run hotter, as the computer was injecting more fuel in to cool it (when it was unnessacary).
Replace ECT sensor. (engine coolant temp) They are cheap and easy to install.

pierre

I checked the resistance of the mechanical fan and it was almost easier to spin it after the engine had warmed up. I think I'm going to replace the fan clutch and see if that helps

pierre

changed the fan clutch and it didn't do a thing. plus now if i accelerate too hard from a stop it sounds like the fan blades hit something metal. i let go of the gas immediately and the sound stops.

i looked at the fan and around it and didnt see any damage. i wonder if something is happening inside the bearing?

dougfrompa

On the radiator there is a vertical support about 1/4 wide right in front of the fan. Check to see if the rivets came loose or rusted off. I replaced my radiator and that support broke loose and made the same noise when accelerating. Drove me nuts looking for the noise but that was it.

dougfrompa

remove the water pump and inspect the blades for rust or damage!!!

pierre

I was looking through my threads and figured I would explain what came of this problem. I know it's 6 years later but maybe it will help someone who reads this.

The jeep sat for two years because I was told by a mechanic that I had a cracked head or bad head gasket. I didn't have the money to spend on it at the time. So I was preparing to do the work on the head myself but before I did I decided to check over everything again. I took the water pump out, like dougfrompa recommended, and all but one of the fins had rusted away. One of them was sitting right inside the engine where the pump mounts. I ended up flushing everything in both directions probably 6 times. I would drive the jeep for a few days then notice that it seemed to be a little hot, so I would flush more rusty gunk out of it and then repeat. I think I finally got everything out but it took a while. Then I did a 70/30 mix of coolant and distilled water.