REV overheating - normal?

[thoner7]

It’s finally summer here in TN. 90 degrees today. Coming home from a trail, I went 8-9 miles on a major road doing 60 mph. Engine temps shot up and the red idiot light came on as it was overheating. Coolant temps have never been an issue before. I did not expect that, given that the REV trucks should handle Baghdad lol. It hasn't happened before even when I’ve driven faster and longer distances on the highway.

Is this normal ? I’d have to think not.

 

[BKubu]

I don't believe that is normal. It gets fairly hot in Maryland in the summer and, even while driving with the A/C on, my engine temperature does not go over 190 degrees or so.

 

[Karl kostman]

First thing I would do is check out the thermostat and make sure its functioning correctly and opening all the way? If that checks out start looking at the cooling lines and radiator, cooling fans etc. Overheating is to my knowledge never a normal situation!

 

[TOBASH]

Start simple. Make sure you have enough radiator fluid and you don’t have a leak.

 

[Retiredwarhorses]

I’ve had the fan clutch fail on REV’s, works perfectly fine at 45mph and lower….but will over heat at freeway speeds, if everything else checks ok?
id replace the viscous fan clutch

 

[thoner7]

I checked fluids before and after, so there’s plenty of antifreeze. I’ll have to search the TMs later and see where to start. Unfortunately I’m working crazy hours right now and also moving so it’ll be a while before I can get to anything

 

[thoner7]

Forgive me for the newbie questions. But the TM says to “feel the upper radiator hose” as a way to diagnose a problem with the thermostat . Am I feeling fit temperature or pressure of the hose??

 

[Mullaney]

Forgive me for the newbie questions. But the TM says to “feel the upper radiator hose” as a way to diagnose a problem with the thermostat . Am I feeling fit temperature or pressure of the hose??

.
Squeeze it. Does it "give" or not? Is it warm? You might also feel a "surge" when the thermostat opens and slams back shut when a little water passes through the hose...

.

 

[Mogman]

If it's not hot it is not passing water.

 

[Retiredwarhorses]

Nothing slams shut, nothing slams open…thermostats open gradually as temperature increase and is fully open at rated temp of the tstat…the tstat regulates the coolant from the block to the radiator from the Top down.When fully hot and open “operating temp” the system should be pressurized, thus feeling the upper radiator hose should be hard and not soft form the pressured system…if not, it’s usually from a bad radiator cap not holding pressure or even a loose hose clamp or even a cracked overflow tank..I’ve seen it all.
And, as I previously stated….ive seen bad fan clutch on this model truck truck on several occasions, again…only at freeway Speeds, generally overheating happens at any speed,

 

[thoner7]

I
had a chance to get the truck out yesterday. I drove it 20 mins accross town, kept it idling and felt the rad hose. I could squeeze it for a good 4 Mississippi before it was too hot to tolerate.

I didn’t know if it had heated up enough, I put the truck in second gear and drove another 10 mins at about 2800 rpm. I did this to simulate highway rpm’s even though I only had winding country roads. I took a pic of my temp gauge at the end of the drive to show how hot the truck was.

same thing. Rad hose was slightly hot but not burning. I’m a novice, but was expecting more like scalding hot. The hose was under more pressure than while cold, but I was still able to squeeze it and compress it. The GFD was engaged and the fan was spinning.

 

[Jinx]

Not sure if your truck is similar to mine or not but you can really hear when the radiator fan kicks on. It's like the truck has a second engine. lol

Do you know if the fan is turning on when the engine gets hot?

 

[mrfarb]

Not sure if your truck is similar to mine or not but you can really hear when the radiator fan kicks on. It's like the truck has a second engine. lol

Do you know if the fan is turning on when the engine gets hot?

REV trucks have a different fan system, that roaring fan isn’t part of it. Has a direct geared driven fan with a viscous clutch.

 

[Retiredwarhorses]

I
had a chance to get the truck out yesterday. I drove it 20 mins accross town, kept it idling and felt the rad hose. I could squeeze it for a good 4 Mississippi before it was too hot to tolerate.

I didn’t know if it had heated up enough, I put the truck in second gear and drove another 10 mins at about 2800 rpm. I did this to simulate highway rpm’s even though I only had winding country roads. I took a pic of my temp gauge at the end of the drive to show how hot the truck was.

same thing. Rad hose was slightly hot but not burning. I’m a novice, but was expecting more like scalding hot. The hose was under more pressure than while cold, but I was still able to squeeze it and compress it. The GFD was engaged and the fan was spinning.

well, that’s one way to get a new transmission out it…

 

[thoner7]

So regarding fans…. Mine spins all the time. As soon as you turn the key the fan starts. Is that normal for the geared fan drive? I’m guessing it’s not.

would a bad fan clutch on this thing cause it to run continuously then give out on the highway?

 

[Retiredwarhorses]

So regarding fans…. Mine spins all the time. As soon as you turn the key the fan starts. Is that normal for the geared fan drive? I’m guessing it’s not.

would a bad fan clutch on this thing cause it to run continuously then give out on the highway?

You have a viscous fan clutch, they are always on, lock up varies based on the heat that flows across the unit.

 

[thoner7]

For the life of me i can’t find the parts list for the Rev trucks. Where would I find the fan clutch part number for the heated fan drive?

which TM has the parts for the REV trucks? I’ve clicked through all the ones labeled as such but I must have missed one.

and just to confirm 12551497 is the proper part number for the 6.5 thermostat? Or is it 12559337 ? Or neither? Depending which TM I’m in there’s different numbers.