Explorer overheating? Help!

[Charlie]

Well, heres the story. I went on a trip today, about 120 miles. Explorer running like a champ throughout the whole thing.

Tonight, I go and fire up for a 15ish mile drive. It is a brisk 30 degrees out, and I am driving easier than usual. The temperature gauge started out low, and then proceeded up to normal range, at a normal speed. Then, continuing up at the same speed, it goes up and hovers just below the red. That is where it remains until I get on the interstate, where it moves up a little bit, and my check gauge light goes on. That is how I noticed it. When I went back down to slower revs, the temp gauge dropped just below the red, and stays there, unless the revs are consistently above about 2k rpm.

I stopped, and checked the engine, and the radiator fan was blowing full, but the engine did not seem particularly warm, and it did not smell funny, nor was it leaking anything.

Any ideas what this could be? I was thinking it was a faulty sensor, but I don't understand why it would go so quick. My only other thought would be a plugged/bad radiator, but I wouldn't think this would come up so quick.

Thanks
Charlie

 

[IZwack]

Thermo of the stat type

 

[Charlie]

Would it really go that fast and unexpectedly? It seems like the temperature gauge is acting normal, in how it moves, just higher on the gauge than it should be.

 

[IZwack]

Well if a large piece of debris settles on the thermostat (as they sometimes do after being dislodged from the walls of the radiator), then its not like a thermostat is going to slowly give you warnings of failure. Also, as the thermostat is heated, its components expand (as with most things) allowing particles to catch in between its moving parts. And when the engine is shut off and is cooled down, the tiny particles get trapped between these parts and will often prevent the thermostat from opening again.

Thats my first guess and its $20 for a thermostat so even if its not, then you've already replaced something for the next tune-up.

 

[Donner]

I had a 96 sport 2wd that did the same thing... thermostat froze overnight and cracked. And forgive my lack of tech knowledge, but coolant was spurting out of something toward the back of the engine (I believe toward the back)... It happened in one freeze. I think when I turned the heater on (or off, I don't remember), it would stop leaking and the temp would settle to normal levels.

 

[Charlie]

Well, tomorrow I will look in to a new thermostat, and also check around again for leaks. I will also check the coolant, make sure it looks ok. If I cannot get this taken care of tomorrow, is it a major problem to drive 100-200 miles with a bad thermostat? AKA I need to get back to school tomorrow.

 

[IZwack]

is it a major problem to drive 100-200 miles with a bad thermostat? AKA I need to get back to school tomorrow.

Lets just say that your priorities have now been rearranged You can't drive this vehicle almost at redline for that many miles -- so you must look into it.

Tell Little Red that the big "bad" wolf really inst all that bad of a dude so she can deal with him, you've got other fish to fry tomorrow.

 

[Charlie]

Well, that is about what I expected, but who knew. Oh well, I guess I have some work to do tomorrow.

Tell Little Red that the big "bad" wolf really inst all that bad of a dude so she can deal with him, you've got other fish to fry tomorrow.

umm, what?

 

[Donner]

How'd it go? Any pics? Did it stop leaking when you turned off the a/c or heater?

 

[Turdle]

You might also check your lower radiator hose-they sometimes collapse under suction when warm--but definitely change the thermostat also--

While you are at it a coolant flush is a good idea--

 

[JDraper]

.... is it a major problem to drive 100-200 miles with a bad thermostat? ...

Not a problem at all.....if you don't mind installing a new motor afterwards....

If you try to drive it that far on a bad t-stat you will end up walking most of the way. If it's stuck shut or blocked you WILL destroy the motor. Hopefully you haven't already warped the heads.

 

[Donner]

Drove 600 miles straight...

I drove from So Cal to No Cal w/o problems... as I recall, I had to not use the heater/ a/c controls. My engine was not affected... It took a couple of days to go get it fixed, but it never stalled. I'm not a tech, so I don't know, but did I luck out?

 

[Charlie]

Well, new thermostat in. Still doing the same thing, and when the gauge is reading in the "normal" range, the heat is not yet hot. It feels normal once it reaches the high range of the gauge.

All of the hoses are good, no kinks or anything, and still no leaks with the coolant. It seems more like there is an electrical problem, either too much or too little resistance on the feed going to the gauge.

 

[mawrazen]

Try an after market temp gauge. $10-15 at parts stores. This should verify if the truck is trully overheating. Good luck.

I installed a 12v aux pusher fan that I pulled from a Subaru at the boneyard. I installed it in front of the of the relocated stock tranny and radiator. I was having problems with the tranny overheating towing a boat up the mountains. Not a problem anymore.

 

[Charlie]

I think I will go for that, just because I am not sure if I can trust the stock gauge anymore. I am pretty sure it is not actually overheating, but it is good to have the peace of mind. Any ideas what could be wrong with the gauge?