bigbernie

I'm just gonna come out with it....
HELP!

My '04 Laredo is overheating at idle. I have replaced the radiator, water pump, thermostat, hoses, heat sensor, and fan (Electric. There is no clutch fan).

The fuse and relay is working.

With all that replaced why is it still overheating?

Any ideas will be greatly appreciated.

4.3L XJ

Well, I am going to say based on the 99 we dismantled here, that there is supposed to be a mechanical and electric fan. I think there is supposed to be a hydraulically driven fan that runs off the power steering pump on the 04 with electric backup when it gets a wee bit warm.

dave1123

Jeep mucked around with different types of cooling fan systems during the period of the WJ. In 99 both the 4.0 and 4.7 had both clutch and electric fans. In 2000, the 4.0 had only an electric fan while the 4.7 still had both. In 2001 the 4.7 had a hydraulic fan and the 4.0 still had an electric fan with a different type of controller, and that's where my knowledge ends.

The 4.0 water pump still has the threads on it for a clutch fan and the clearance to swing one as well as the electric one. Some of the trailer tow packages had extra cooling, but I never saw one like that so IDK what that entailed.

There is another possibility. Are you sure you put the right water pump on it? The earlier 4.0's with the v-belts run in the opposite direction than the serpentine belt pumps. They don't pump properly running in reverse.

bigbernie

All I know about my Laredo is that everything worked fine until the original radiator sprung a massive leak. It never overheated once in the 1st 2 years. Then the radiator split along a seam. It never had a mechanical fan for as long as I've owned it.

I replaced everything trying to chase down the source of the overheating. And that's when the problems started. The entire front portion of my engine is less than 6 months old. 1st I replaced the radiator and hoses. Giving it a flush. Then the fan. Then the pump. I thought I finally found the problem when I replaced the thermostat. No overheating for 6 days.

Then bang. Overheating. Now though, it will start to boil over even while moving.

I am completely stymied.

P.S.

It also has the weirdest radiator setup I have ever seen. Both the transmission and the AC compressor line feed into the radiator. The tranny lines on the driver's side and the AC lines on the passenger side.

Jayjr

did you ever figure out your problem, i'm having same problem

dave1123

I think that's wrong. The radiator and the A/C condenser have 2 separate functions. The A/C refrigerant has to get rid if it's heat and return to a liquid in the compressor so I can't see it passing thru the radiator and getting heated before going to the compressor. The radiator and condenser may have been replaced as a unit, but have to be totally separate parts.