Well after dilligently searching around the forums I have decided to try the fan-clutch next. I replaced the thermostat earlier today because that was my first instinct, but its still heating up.

Symptoms: Heats up after initial warm up in highway driving conditions - especially when going up hills.

Clue: Fan seems to spin fairly freely when engine is off, but still at operating temp.

Am I on the right track here?

Thanks for your help!

 

if the fan clutch spins freely it is bad. although on my truck when it went bad it would only overheat when i was at a stop for to long like in traffic or at the drive through. i bought a replacement at autozone and went through 3 before i got a good one from napa.

 

Ok, lemme get this straight. You are overheating and having idle issues? Sounds like a possible blown HG.

 

Wouldn't I have other symptoms (milkshaky oil/coolant, white smoke, etc) if I had a bad HG?

 

Does sound like the fan clutch is bad, however not the original problem. You should not be overheating so easily.

When you say overheating, how overheated? If you don't have a bad HG now, you may have one soon before you fix the original problem. It is heat that kills the HG. Worse, if you lose the HG, you risk a scored piston or worse.

Do you have any coolant loss? Of course you will, if it gets into the red, but otherwise you should not lose coolant except over many miles.

 

I think you might be off-track......I say that because if your overheating occurs at highway speeds where there is a good wind blowing thru the radiator, then airflow is not the prob. This is assuming your radiator is not clogged with mud or leaves thus preventing airflow. In other words, fan clutches may not even be required for highway driving.
A radiator with high miles can be partially clogged with lime/calcium deposits causing overheating mostly on the highway. When it gets hot again, take note if there seem to be cool spots on the radiator.
My radiator had 230,000 miles on it and it over-heated too many times on my 87 22RE Runner and that ended up causing a HG issue. A new Rad and HG fixed me up.

 

Regarding how much it overheated - I shouldn't say *over*heated. I should say it gets too hot. Turning on the heat or babying it seems to help it from truly overheating. I would sooner pull over than let it get in the red.

The radiator definitely could be a problem too.. Your absolutely right, but based upon the free movement of the fan.... I want to replace the clutch first. Maybe I should just do them both at the same time.... I don't know. I'll get prices today. Where do people like to get their parts?

I understand what you are saying about the fan not really being all important on the highway, but when you look at the front of the car there is a lot of stuff the air has to get through in order to successfully cool the car. I'm no engineer, but the fan probably helps guide the air through the radiator at speed, so that the air doesn't just make its way over and beside the car. (Anyone feel like renting a wind tunnel?) Or does this sound completely off?

...Thanks for your help!

 

Are you replacing coolant?

 

When I changed the thermostat yesterday, I put pretty much all new coolant in it. I didn't mix different colors or anything like that. The only weird thing I did was use some water wetter stuff that I put in my other ride. (its good stuff.. I recommend it!)

 

[hijack]
i was hoping to hear that.. i've been over heating when coming to stops at drive thru's and i thought it was the fan clutch.

thansk
[/hijack]

 

I think ZUK is on the right track...

I had the same problem with running hot at highway speeds or under load... hills, hauling etc.. I tried to fix it by changing the thermostat and after that the rad cap.
(tried low cost stuff first) I finally ended up taking it to a rad shop and the guy said plugged rad.

Seems that the top of the rad was too hot to touch shortly after warmup, while the center portion of the rad was almost cool or luke warm and easy to touch and hold your had on.

I heard of another way to determine if it's a plugged rad, but can't say I remember how it's done (good memory just short) Something to do with a garden hose and spray the front of the rad...

I'm not sure the age of your truck, but mine's a 1991 V6 and it was around 2003 when I had the trouble. Replaced the rad and it hasn't missed a beat since. I have around 333K Km's on this engine, and replaced the head gasket back at approx 124K Km's.

Chow for now

 

If you are adding coolant, you need to determine why. It has to go somewhere, and where it goes is important.

 

When I had an electric fan and drove on the highway it would ONLY kick in when I pulled a 3000 lb trailer. Otherwise it would never come on as there was enough air flow to keep things cool.

 

I HAVE v6 radiator for sale. i bought a v6 radiator and didnt' realize i already had one!

 

thats great. I too have a problem with the hill issue. i replaced the cap,thermostat.noticed that someone had flushed the rad back in 03' (gloove box clue).now here in misery, a little up the hill will have the temp in the 3/4 zone. i changed to syn. valvoline hoping that would help.maybe the fan is the prob. no leekies,that is see or loss.would and electric fan fit somewhere in this tight az spot.??i have an auto also...

 

sorry i highjacked your thread,,,

 

I must be missing something...

The whole reason the fan has a clutch is so that it freewheels when extra cooling isn't needed to save strain on the engine and increase fuel milage.

Are you saying that when the engine is hot and the fan should be on that it is stopped?

When the engine is cool and off, the fan will freewheel...

I'm going with either getting the old radiator rodded out and rebuilt, or getting a new one. Depending on how the truck has been treated, that rad is plenty old enough to be shot.

 

Correct. However it gets a bit tricky to give advice on this, as most of us have the opposite problem, the clutch is staying engaged when its not needed.

So we don't see a heating problem associated with incorrect fan action, and are therefore suspicious of something else being wrong.

If the fan problem is new and the heating problem occured at the same time, I suppose that is a reasonable concern.

As others have said, ideally, if you go through a warm up cycle the fan should remain off, and engage after a fairly long idle time.

Since there are so many other causes of overheating, it would seem likely something else is the problem. And when you say you lost coolant, that is a possible red flag that you should sort out.

Again, as others have said, normal highway travel on flat ground should not cause overheating, fan working or not.

 

I just had a very simular problem and it turned out to be a cracked head instead of a HG. Hope you dont have this problem it cost about $2000 with a used head instead of a new one. Good luck.

 

rcm----any updates?