Running Hot

[96ExpXLT]

I am having some trouble with my 96 XLT. I have a 40 mile drive to and from work. On the way to work, the temperature guage never rises above normal (slightly less than 1/2 way), but on the ride home, the temperature guage has been getting pretty close to the top of the guage. I even heard it slightly boiling over when I got home. So it is actually getting too hot. Not just a guage problem.

I replaced the thermostat a few months ago due to a different overheating issue, and that seemed to fix that probelm.

I am guessing it is a clogged radiator, but before I replaced it, I thought I would check for any other suggestions.

Thanks.

 

[FU MONSTER]

could be clogged. How old is the water pump?

 

[96ExpXLT]

Water pump is original, so 14 years (give or take).
So is radiator.

Got over 250,000 miles on it before odometer stopped working about a year ago.

 

[FU MONSTER]

Could be either of those. I would try doing a coolant flush. that might help.

 

[Blee1099]

I'd check the fan clutch, if its a 96, chances are the fan clutch is probably on its way out.

 

[96ExpXLT]

Fu Monster -
If it was the water pump, wouldn't it over heat very quickly, and why would I see such large differences between morning and afternoon driving? This is during about a 50 min drive at highway speed. One difference is that there is a 70 mph section (~15 miles) at the beginning of the morning drive, vs at the end of the afternoon drive. Not sure if that would make any difference.

Blee1099 -
How do you check the fan clutch?

Thanks.

 

[96ExpXLT]

I checked the fan clutch before going home from work. The fan spun relatively easily but with some resistance. There was no wobble to it. After getting home, the temperature gauge was almost in the red. I checked the fan again, and it turned with what appeared to be about the same amount of resistance. It was not hard to turn at all.

Should it have been hard to turn?
Does this mean that the fan clutch is bad?

 

[Blee1099]

On a good fan clutch if you spin the fan by hand from the 12 o'clock position it shouldn't go past the 10 or 2 position. Best thing to do is find another Explorer and compare how much it spins. Another thing to check is the thermostat..

 

[96ExpXLT]

That is about the amount that it would spin. I would say about 1/4 turn before it stopped.

So I am thinking the fan clutch is ok.

The top radiator hose line was extremely hot when I got home. Basically too hot to touch. So I think the thermostat is opening. I base this also on the fact that the temperature does not overheat on the drive to work. If the thermostat was not opening, I would think it would overheat all the time. It is one of the cheaper versions, and I have recently read some threads indicating the "need" for the motorcraft thermostat in the Explorers. Since they are relatively cheap and relatively easy to replace. I will most likely replace that too.

Is there anyway to determine if it is a clogged radiator?

It just seems like it is very gradually heating up, especially in the warm afternoon weather (100 F today). So I thought that the radiator was clogged and not cooling the coolant as it should. The fins on the radiator were not warm yesterday. Did not check today.

 

[96ExpXLT]

Any suggestions on diagnosing a clogged radiator?

 

[96eb96]

Any suggestions on diagnosing a clogged radiator?

Here are some suggestions...

Pressure test the system for external and internal leaks. Some of these engines at very high mileage have issues with heads cracking.

The motorcraft Tstat has a bleed hole, and these 4.0L engines have issues with air pockets. The Ford part has been revised many times, it may be a good idea to change it.

I use an IR thermometer to check radiator inlet and outlet hoses. Obviously you should have a nice temp difference.

At this point I would pull the radiator and give it a good 1/2 hr BACKFLUSH (and the heater core too while its apart, but very low pressure) with a garden hose. No one does that anymore when they change coolant. Can't hurt!

If that don't work at 250K I would move on to the waterpump.

When the car is hot, the fan should be blowing lots of air to the radiator with authority and roaring like storm. Its usually hard to mistake if its not working properly. There is a newspaper test (at your own risk), when its hot - a rolled up newspaper with light to moderate pressure should not stop it. Caution applies here. use eye protection..and I do this test towards the center or stronger part of the fan.