Engine/Transmission (1998.5 - 2002) High engine temp.

[Blue Thunder]

When towing my trailer (20K+ lbs. GCVW) over long grades, my engine temp climbs to scary levels. Both times I pulled the grade out of Pismo Beach, CA (northbound hwy 101, don't know the name of the grade, but it is about a 8-9 % for 5 miles) my gauge nearly pegged to the point that the 'check gauges' dash light came on.



What can I do to keep temps down???

 

[InThinAir]

Sounds like your fan is not engaging. There is a clutch test procedure, do a search to get the exact process, it is too late for me to remember right now. But that would cause a real high water temp. Also those pesky radiators do need a good cleaning from time to time. But that would only make your truck run a little hot. Next thing to replace is the thermostat but that would make you run hot most of the time not just towing. Well I am awake enough to say now, yes it is your fan clutch.



---Doug

 

[Blue Thunder]

I should have mentioned that I had the fan clutch test procedure done and it checked out fine, and I also had the radiator flushed and the t-stat replaced.

 

[Turbo Tim 1]

36 inch tires and 20,000 lbs your working that truck some! Most people immediately think that there cooling system is to blame when they get high engine temps but as I see by your signature you have an automatic transmission, right there lies your problem most likely since everything else has been checked. Have you got a transmission temp gauge? I'll bet it woulda been pegged during that climb! Your coolant cools your trans fluid but when she climbs up well over 200 degrees it now heats the coolant. Twenty bucks says that's what's happening.



As a side note I would seriously watch those high temps pulling grades there has been a few people around here that have burnt up some pistons doing that when most things looked ok by the gauges. I am going to assume you've got at least an EGT gauge. What kind of EGT's are you running?

 

[willyslover]

you have enough fuel to heat things out of sight... DO NOT use all your power or your going to loose a motor. .



best to gear down to 1 to 1 [v/s overdrive] and back out of the loud button. . your DDIII's will take you way past 1300 and that grade will toast you !



what gauges are you running to help you ?

 

[Lsfarm]

Outside of Radiator

When you had the radiator flushed, was it pulled from the truck ?? If so then the outside of the radiator would have been cleaned.



If not, then I would recommend pulling the radiator itself, it's not a tough job, and cleaning the outside fins. They usually are all crudded up with dirt and bugs that have adhered to the oil coating from the blowby bottle. I'd also remove the blowby bottle and extend the blowby hose down to the bottom of the engine, keeps the engine and radiator clean.



I pull with BD3's and if I keep the box turned down, the EGT's stay under control.



Hope this helps. Greg L

 

[Blue Thunder]

I usually keep the box off while towing. I've climbed the grade twice now and am planning to do it again in a couple of weeks. The first time, no box, the second time with the HX-40 and the box on the lowest setting. No difference in temp.



I have boost, trans temp, and EGT gauges. I bought the HX-40 to try to help with the high egt's. The last time I pulled this grade, I kept the egt's under 1300, which meant less than half throttle, once speed dropped below 45 mph. Trans temps were never too high to worry about (<220 deg. )



It does make sense though, that the trans fluid could cause engine temp to rise, given the locations of the coolers. Should I put an aux. cooler on?



B. T. W. I am having the gearing changed to 4. 30's this week. I think this will improve towing overall.



Any other suggestions on how to keep temps down?

 

[Lsfarm]

Trans temp where?

Where is you trans temp being read?? if this is in the pan, then you are running REALLY hot [this reading is after all the coolers]. If this 220* reading is in the cooler line leaving the trans, then it still is pretty hot, I wonder if you have an electrical problem that is keeping your TC from locking up?? If you are in Lockup, your trans temps should be only around 150* either in the line or the pan.



Do you either have a lockup switch or some kind of TC controller?. If you have the TC unlocked during the climb up this hill then you will create a lot of heat, and it will be shed into the cooling system through the heat exchanger.



Whatever you are using to lock up the TC, check to make sure that you aren't pulling this hill unlocked, if you are unlocked then just lock the T/C and your high water temps will be GONE!



Your 4. 30 axle ratio change will help, but something isn't right. When your temps get this high, do you hear the fan clutch engaging?? It sounds like a jet engine roaring, startled me the first time I heard it, very loud.



Did you check to see if the radiator fins themselves and the A/C condenser and intercooler fins are clean?? It doesn't take too much to create a significant blockage of the fins.



BTW I pull at around 17K GCVW, at 70-80 mph, locked in OD, and never see above 150* trans temp or above 190* engine temp, and I have an electric radiator fan. While I realize I'm not pulling 8% grades for miles, but I never see over 150* trans temps when towing except from stoplight to stoplight, then 220* in the line temp isn't unusual.



I'm not familiar with the front bumper you have, does it have openings like the stock bumper for cooling air to get to the bottom of the condenser/intercooler/radiator?





Hope this helps Greg L.

 

[SGoodman]

I was coming home a few days ago and it continually ran at about 200-210, then on one hill climb it peaked at 220 or a little higher. This is the highest I have seen with this truck so it made me a little nervous. But the fan kicked in and if I backed of a little it went back down. I was running fast and unloaded with a 6spd, and it was about 85 outside. Time for gauges?

 

[Lsfarm]

Read above posts

SGoodman, read both my above posts about clogged radiator fins. If you haven't moved the blowby bottle from the front of the engine, then you probably have plugged, clogged radiator fins.



Use a good degreaser/solvent and low pressure water or air to blow out the crud from the fins. High pressure can bend or distort the fins.



An empty truck should run at 190* even at 110* ambient temps.



Blue Thunder? did you verify that your trans TC is locked when you are climbing these hills?? Pm me if you have a DTT smart box, I'll help you adjust it.



Greg L The Noise Nazi

 

[OTRPU]

Brandy new Cummins in my '99, just hooked to a 28 ft 5er and ran I-80W, Bristol, IN to Kaysville, UT. Ignored listening to weather reports, wind through Neb like to blowed the 5er to pieces. Things like vinyl welt blowed out of the leading edge channel driver side of camper. It stayed connected, but beat against the side of the camper and knocked the left frontside ID marker light lens off and light quit working. Also all the screws came out of the leading edge aluminum sheeting that rolls under the front of the camper. Anyway, OTRPU ran like a scalded ass ape. Knew the 5er was there, but didn't care. Before I noticed EGT's bounced off 1,400 degrees F. Dropped her out of OD and backed out of the throttle enough to get temp down to 1,250. transmission temp not even 150 degrees. Engine coolant temp half way up the range on right side. Next stop for fuel I checked oil, after 500 miles she was down a half quart. Angola DOC, Dave's Diesel says he's turned the Edge down to keep me from twisting the EGT pointer off the pin. I was cautious and self controlled the last 1,000 miles of the trip and dropped the trailer at the dealer. Return trip MT (empty), I watched everything closely, everything seems to be ok. Think I'm going to get OBDII software for my laptop. I run a laptop log anyway, might as well have the additional information. What's available that will give me the information I need, both engine and transmission? I'm starting to question my sanity. I think I'll stop by my Denver DOC, Reliance Truck & Auto and see what codes need to be cleared. A question for the Guru's, looks to me like too much fuel or not enough air, what's a rational solution? Larger turbo? Or a block of wood under the throttle?

Blue Thunder, what differences do you see with the 40?

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Cheers,

Steve J.

 

[Blue Thunder]

Lockup is confirmed in 3rd. But, at 35 mph, the trans is in 2nd. I thought that our autos never lockup in 2nd. Am I wrong?



I am not running any lockup device presently. Would that help in this situation?



Temp is taken from the pan.



I will clean the radiator and fan fins today.

 

[rblomquist]

Sounds almost exactly like what I was experiencing last summer before my stock trans started to go south. After I got my new trans my temp never has broke 190 and the trans fluid in the pan this time of year 90-100 degress hovers around 160-165 towing my trailer at hwy speeds. The temps you're describing (both coolant and trans fluid) are way out of norms.



Also, check your exhaust manifold for loose/missing bolts. I've heard of trucks exhibiting weird tendencies because of cracked, loose and/or misaligned manifolds.

 

[barepa]

Is your therostat a 180 or 190, a bad therostat thats not opening all the way is hard to find. even new ones can be bad. I went to a 180 took care of my heating problems. like night and day.

my 0. 02

Dave

 

[rweis]

Your temp is in the pan and it is 220*. The hot line is REALLY HOT! I would bet your fluid needs changing from being burned.



The aftermarket trannys can lockup in 2nd. I don't think stock transmission can without some sort of an aftermarket lockup device.



Probably your engine temp is going up because of really high transmission temps. Even with your fan ok.



To get rid of transmission temps you have to lock it up. Rebuild transmission, lockup device, something. I would call DTT and ATS to see what they think can be done.



After the transmission is locking up then see what the temps are.



As stupid as it sounds, there is quite a bit to do to get the use of what the CTD can produce in power. Clutches changed, trannys rebuilt, gauges, aux coolers, injector / fueling boxes etc.



I would start with getting the 2nd gear lockup addressed.



. 02



Bob Weis