Engine/Transmission (1998.5 - 2002) Overheating while towing

[Mike760]

My truck is overheating. It only seems to do it when I am towing. Even with an empty trailer it will start to heat up a bit. As soon as I hit a grade it will gradually overheat after a few miles. My empty weight for the truck and trailer is 16,000 pounds. I have flushed the cooling system, replaced the thermostat and put in a new fan clutch. I also put in a cooler mix which actually droped the temp to around 170 or 180 when not towing. Any ideas?

 

[ProspectorTim]

Replace the radiator cap?

What gears do you have in the axles? Those 35's could be hurting you if you are geared high (but may be ok with 4. 10's).

Have you cleaned the bugs and road-grime out of the radiator fins?



... so much for the cheap stuff...



Beyond that, you may have torque converter or transmission internal slippage causing heat. I am not familiar with the characteristics of the "Mopar HD Torque Conv" , and you didn't mention how many miles are on the truck and/or transmission. You may be overdue for an aftermarket upgrade - trans, VB, TC, etc.



When you say "overheating" I assume you are talking about coolant temp, since your signature doesn't mention gauges. However, if by any chance you are talking EGT, check for loose clamps on the intercooler hose connections.

 

[JBlock]

You might want to try adding redline coolant acccelerator.



Mine does it too, when towing I see higher temperatures, if particular if I running in second, which is unlocked the transmission temperature seem to be driving the coolant tempertures up. I planning on adding a cooling fan on the transmission cooler, it way out of the air flow if your going slow.



JB

 

[RHARVEY]

When the temps start to come up... do you hear the fan clutch lock up???





Rick

 

[Mike760]

Yes, it is the coolant temp. I have not put a new cap on. I did clean out all of the bugs, dirt and other stuff. I can see light through the front if I put a flashlight inside so I think it is pretty clear. One thing that I do not hear is that fan clutch lock up. I used to hear a big roaring sound and the temp would drop like a rock. That's why I had the fan clutch replaced because I thought that it was no longer working. The joint where I had it done said that if it is working properly I shouldn't hear a big roar but I disagree based on the 100's of 1000's of miles that I have towed. The truck has a little over 150K on it right now. I had the trans rebuilt at about 125K. I am not sure about the ratio and I guess I just never really checked. Where do I find that out?

 

[Tcolesanti]

It should say your gear ratio on the inside of the glovebox door. You definatly have a problem with your fan clutch.

 

[Todd T]

my vote is clutch fan too. do you have a transmission temp guage? you could be pooring a ton of heat into the rad from the transmission running hot on ya. you might want the check into that too.



these trucks have huge radiators. shoot you can almost run around without a fan at all and not have a problem. I would check into the transmission temps ASAP.

 

[tractorface]

clutch fan!

Just cause it was replaced does not mean it works. Next time you are out as soon as you shutdown the truck pop the hood and try and spin the fan. If it spins freely you have found your problem. This of course assumes the truck is up to temperature when you shut er down

 

[RHARVEY]

I would guess that if you replace the fan clutch your heating issue will go away!...



Advantage Dodge in Farmington New Mexico. . 800-748-2139 and ask for internet parts sales...

The last one was $142. 00 sitting on my door step. .



Rick

 

[WestTN]

If you don't hear the roar of the fan then it is not turning fast. The fan clutch is the wrong one or is defective. The stock fan clutch engages when the air passing over it reaches 206 degrees F.

 

[kacee3759]

I had the same problem you seem to be having. I went through all the same fixes but no help. My problem was solved when I replaced the 190 degree therm. with a 180 degree one. Don't know why, maybe the 190 was bad but the new 180 did it. My old trailer truck rig together was about 16,000 lbs and my new one is around 20,000. On the worst hills, reved up for several miles no problems now.



Good luck,

Kary

 

[ProspectorTim]

One easy test for the fan clutch is to watch it or listen when you shut the engine off. When cold, then fan should freewheel several revolutions. When hot, the fan should stop turning instantly, and the belt should chirp.

 

[Mike760]

Well, I know I can stay cool with my current setup because on one load that I was pulling a while back, I scaled at about 28,000 pounds and I was crawling over some very steep grades at 20-25 mph in Idaho and the temp didn't even budge. The only thing is that it was only about 10 degrees outside up there and down here it has been in the 80's and 90's for a while. I don't recall if I heard it lock up or not. I just know that I haven't heard it in a while now.



The engine has been shut off for about 3 hours now and is warm to the touch. I spun the fan with my finger and felt some resistance. It did not spin freely. It stopped instantly after my finger left the blade.



If the truck is cold and has just been started, I can reach in a grab it and it will stop without taking off any fingers.



I ordered my trans, boost and pyro guages last week so they should be here any day now and I can post some readings next week. I'm leaving for Las Vegas in a bit. Good thing my guages are already paid for.

 

[Snow man]

replace the Tstat,if the tstat isnt opening fully the rad wont get hot enough to engage the clutch fan,even a brand new fan wont engage with a cool radiator. The fan needs to sense hot air to engage. Ive "fixed" a few overheating trucks with a new tstat and cleaning the grease,bugs between fins in the radiator.

 

[Huff N Puff]

I think its your blow-by bottle,that releases a fine sticky mist. The mist is caught up in the fan. The fan plasters this sticky mess into the radiator,which acts like a oil bath air filter that catches all the road debris and clogs up not letting enough air through the radiator. Pull the radiator spray it with a solvent and blast it with a pressure washer. Then remove the oil blow by bottle and extend the hose down and away from the radiator.

 

[RobertMiller1]

35" tires possibly contributing, overall gearing is now higher (numerically lower) equivalent. lower rpm , more lugging (comparatively) lower turbo boost higher egts probably...



just supposition...



thermostat easy cheap mod. Cummins has them. got one myself, haven't put it in yet.



front blow by bottly good advice. empty and hose inside of radiator down at car wash with soapy water. it's the film that insulates. doesn't have to be fully blocked.



get some good transmission fluid. Redline ATF+3 synthetic if you can afford it. www.summitracing.com is one place that carries it. I'm using Valvoline extended life with good effect.



Shift improver kit will keep slippage and friction and resultant heat lower. transmission has oil to water heat exchange... transmission could be transfering heat to coolant.



I'd GUESS tires combo was biggest impact

 

[Mike760]

Like I said, I replaced the stat. I also don't think it is the oil because the minute I got it back after replacing everything including the fan clutch, I hitched my gooseneck and took it up the mountain and it immediately started heating up and overheated by the time I got to the top. And this was with an empty trailer. I never heard a roaring sound when it started getting hot.

 

[Mike760]

I've had the same size tires on there since I bought it. I've towed through almost every state in the country and some in Canada in the last 12 months alone and this problem just started a couple of months ago. I think I need to get this trans temp installed so that I can get a reading and see if that is an issue.

 

[chef]

i'm now planning to do the small things noted in this post. my overeheating fiasco begain in 91 traffic on a friday afternoon towing an 18' flatbed with my trailer, really not all that heavy. the transmission was getting really hot so i pulled over and let it cool off for nearly an hour. finally got moving, soon as i started climbing the grade to big bear the engine temp shot up. i couldn't pull faster then 20. i saw 1200 egt's a few times, tried my best to keep it all low, eventually just pulled the jeep off and had a friend drive teh truck the rest of teh way, no problems after that. now when im pulling a grade it starts to heat up, usually i'm about halfway into the second section on the engine temp guage, it heats up to halfway in the third section on the guage. transmission hasn't gotten over 160 since then either. egt's seem to be a little bit higher then usual and the boost guage flutters sometimes between 8 psi and 16 psi. it didn't used to do this, and being a diesel newbie it worries me. i'm searching trying to find the answer, but any other thoughts on this?



the engine is stock, 4" exhaust, egt, trans temp, boost and fuel pressure guages. fuel pressure is fine, stock tires. . i do have some bug buildup on the coolers, i'll have to clean them all out, check the thermostat, new hoses, and check the fan clutch, although the fan does spin.

 

[johncameron]

Mike 760, Do not try to stop your fan even when your engine is cold. You WILL loose your fingers!!!