Alrighty ladies and gents, I am new to this ball game and I just bought this tricked truck, I hooked on to a 36' fifth wheel about 8,000 lbs. loaded,took it off overdrive, and spooled it up to take on a pretty good incline, monitoring everything, I noticed that the temp was warming up to about 200-210, then the idiot light blinked and chimed as it fell to the 230 mark! I obviously backed out of it and cooled it off at idle then it ran 200-210 as long as I would keep it at about half throttle and really monitored it. (EGT's were always under 950). On the trip i cut out the t-stat and tried just leaving in the restricter plate because I couldn't get a new t-stat in the boonies...no go same results... Got back and changed the fan clutch, it has a new radiator, but what t-stat is best, and what else should I check before tying on to a load again???

 

Only thing left is water pump or a leak. I've had radiator caps not hold pressure but hold liquid. Get the Cummins thermostat..$$$ but touted as the best on this board.

Mine will typically get to 200 when towing up large hills, but that is it. Are you losing coolant? Oil look okay? Any trace of coolant in exhaust?

 

air flow is all you can do and the proper t-stat. if your getting the proper air across the radiator you've got other probs.

 

No sir, the coolant level is fine, and the previous owner stated he had just replaced the pump...Delo Oil looks ok w/o "milk" and no trace of coolant in the exhaust...Which T-stat is best? I almost went with a 180* today, but figured ask around first. Does around $45 sound about right? I'll also put a a new cap... someone recommended an 18 lb....

 

What was your trans temp reading?

Once it gets nice and toasty, you'll see your water temp rise as the trans fluid flows through a heat exchanger.

Once the trans temp falls back down, the water temp will fall as well.


phox

 

Tranny ran at 200*-210* max, I stopped in at an Auto Zone and bought a temp gauge. I by-passed the heater hose at the elbow on top of the head, and capped the steel rail connection. I pulled the fitting, and installed temp gauge on top to monitor it and it raised up pretty good when I put my foot in it both w/ t-stat, and cut t-stat w/ rest. plate only.

 

Go buy a bottle of Watter Wetter made by Redline. It will cut your temps 20 to 50* all else being the same. I run the stuff in all of my sand dune bikes. It helped out a ton on my Dad's Dakota that is always overloaded. If you can't find a source for it, most motocross/atv shops carry it. Maybe autozone and or napa carry it too. It costs less than ten bucks and worth every penny!

 

Check for dirt restricting air flow through the AC condensor, charge air cooler and radiator. I have seen several times where dirt will plug them up and not allow enough air flow through to cool the truck.

 

Do you have a vacuum pump leak, or any evidence there ever has been one?? Most of these trucks have them at some point, and over a short time the oil clogs up the radiator from the engine side. I recommend you take a look at this very closely, it caused all my temp problems. Go to the engine section and find my project 99 thread, it has pictures.

 

Wow, that is quite a bit of oil and grime on project 99, definitely enough to overheat your rig.

I did previously check that for dirt,hay and junk... and there is absolutly no oil leaks under the truck at all. The Cummins t-stat I ordered should be in today, I decided to go with a 180* But still not sure on the cap pressure to try out...hopefully the fire in my engine block will finally go out after I install the t-stat.

As far as the water wetter, I use that in my 454 jeep cj-8, and it does work well, but I was going to wait until the last straw to put it in my truck cooling system.

 

Just curious if you monitor your egts pre or post turbo?

 

mike beat me to it.
water wetter is what i have done. and i am going to put on a cooling mist system and just spray water. if you reduce the cylinder temps, that is less heat the coolant system has to absorb.
you are getting that hot towing 8k? that isnt good.

 

What is the ambient temp outside? Where are you monitoring egt's, pre or post terriblecharger? Is it overheating on flat ground? The high ambient temps of the summer, i.e. 100F and better will overheat just about anything on a hard pull. Higher fuel temp, higher air inlet temp, higher air to air outlet temp, higher radiator cooling air. I dirve a new C5500 Chevy Duramax service truck weighs in at 18000lbs. It will pull up to 220-230 degrees on a good grade if I don't back out. That is stock. Seems like my Dodge will warm up in the summer pulling. Should never exceed 1250F in the exhaust manifold on continuous high load pulls. Take 300 degrees off 1250 if monitoring post turbo. I havn't tried water wetter, but if you are truely just up aginst the maximum cooling capability given all variables, water wetter might help. If you have a cooling system component issue, water wetter probably will not help.

 

My Pyro reading is post turbo, and it reads just about 950*. And yes it heated up on me in Southern New Mexico, ambient temp of 100*, but it did the same thing in the mountains where I ended up, and ambient temp was about 75*.

It will also heat up on flat ground when I really put my foot in it to keep my speed up around 70mph. I know, 8k should be a walk in the park for my rig, I have two jeeps to pull around on a gooseneck....now I am gunshy about it til I get this problem fixed...

 

By this do you mean a water/meth injection system? I am just asking because some stock car guys put a mister with a little water pump in front of their radiator when it starts getting hot, and that drops their temps pretty good also. This would probably work for just a sled truck as well, but don't quote me on that one...