'95 Explorer running too hot

[merc80]

My wife drives a 1995 Explorer with a 4.0L v6. The tranny went out last fall, and it's been sitting in the yard. We got it fixed, but it seems to me that it's running hotter than it should. The temp gauge doesn't show degrees, only L and H. It seems to me that where it used to run about 45% of the way to H on the gauge, it's now 50-60%. On Sunday I let it idle in a parking lot for about 10 minutes, and I had to shut it off because the gauge was up near 75%. I don't know how much of this is just the fact that it's been near 100 degrees every day? Any ideas or suggestions?

A little background on car...Replaced water pump, thermostat, and a couple hoses about 3 years ago. Heater core replaced 2 years ago. I flushed the system last weekend. It hasn't seemed to have made any difference. I was thinking of replacing the thermostat, would a cooler thermostat help? OEM is 193 degrees, but I've seen both 180 and 160 available.

 

[brianl703]

Is the fan clutch ok?

I believe that model does not have electric cooling fans, so it would have a fan clutch and they are known to wear out.

The test is to spin the fan blades with the engine off--there should be some resistance. If none, the fan clutch is worn out.

 

[punisher]

Don't switch to a lower temp thermostat, that is not the solution. Fan clutch is a good suggestion especially with the symptoms you describe. Easy way to check is to let the engine warm up, watch the fan and have someone shut engine off. Anymore than two revolutions before the fan comes to a stop= replacement time. You can also rub your fingers over the front of the fan clutch and see how much silicone oil has leaked out.

If you know someone with a scantool with data access you can look at the "ECT" data and compare that to your gauge. Not unheard of to have a bad sending unit or gauge in those.

 

[Dave H]

I doubt a cooler thermostat would be much help. At most, it would be a band-aid on a bigger problem. And it could cause the engine to never reach operating temp, so you'd always be running rich. This would depend on the vehicle and it's computer.

I agree with brian on the fan clutch. I recently went through this ordeal on my wife's '88 Nissan pickup. It wasn't particularly overheating, just the gauge going up to 3/4's at highway speeds and whenever the AC was on. Fan and clutch (an integral unit) had been replaced, thermostat twice, both radiator hoses, several flushes (including the Zerex or Prestone Super Flush stuff) to no avail. I made a thread on here about it, and several members (I forget who now) mentioned replacing the radiator. Had to do with the radiator being partially clogged, and at highway speeds (increased rpm) or with AC on (increased thermal load to the radiator), it just wasn't able to keep up. Replaced the radiator, and everything has been fine for several weeks. It is actually odd to see the gauge not even getting to half-way, no matter what the speed, AC position, or whatever.
Since thermostats are relatively cheap, I'd start with just replacing it. You could test it in very hot water to see if it opens, but you still have to do the labor of taking it out. So I'd just swap it for $5 with a stock one. Double check your hoses, especially the lower one which may collapse when the engine is being revved. Has to do with the inside getting weak. Also test the fan clutch as brian said. If it spins freely when the engine is off, replace it. If all else fails, think about replacing the radiator. Shop around for the best deal. My wife's from Advance Auto was $124, and has a lifetime warranty. It was also a perfect replacement.
Interstingly, a shop my wife took her truck to had a different test for the fan clutch. With the engine idling, the mechanic reached down and grabbed the fan. It stopped. He said this meant it was bad. Personally, I don't think I'll be attempting that type of test. I also wouldn't advise anyone else to, either, because what happens if the fan is good? That shop also failed to fix the problem after replacing the water pump/fan clutch, thermostat, and both radiator hoses. I had even told them I had replaced the water pump and thermostat previously with no effect. I swapped the radiator in less than 30 minutes.

Hope this helps.

Dave

 

[mjpolge]

Another point to consider is air lock. Is all of the air out of the system after the flush? That caused a lot of problems when I had my '81 vette.

 

[merc80]

I went out this evening and I tried spinning the fan with the vehicle off. The was a moderate amount of resistance, it probably made about 1/4 revolution from me spinning it. I had noticed a few very small hairline cracks in the fan, but didn't think they were big enough to be a problem. Given the age and mileage (250k) of the vehicle, I should probably replace the radiater anyway.

mjpolge- How did you get the air out of yours system?

 

[Clyde65]

I'd convert over to electric fans. I'm thinking the set-up of the later model Explorers should work fine.

 

[brianl703]

Sounds to me like the fan clutch is slipping too much..on my Mustang I cannot spin the fan by hand fast enough to keep it moving once I take my hand off of it.

 

[CBDFrontier06]

My roommate's 99 Explorer 4.0 started doing that same thing, and I immediately went to the thermostat. It had come apart and pieces of it were bouncing around in the housing. It's easy to get to, so give it a look.