Overheating while towing

maddog411

Well-Known Member
Joined
Mar 22, 2005
Location
Harrisburg, NC
I have a 2000 Dodge Ram 2500, 5.9 Gas V8, 4.10 gears, 35" tires, 5 speed manual for a tow rig.

Towed my other truck and trailer (maybe 7k) up I-77 thru Fancy Gap, VA a couple months ago. Fancy Gap is like 6% grade for 7 miles. Had plenty of power in 3rd but the temp got to the top of the normal range (about 240 degrees) and I had to downshift to 2nd.

Replaced the fan clutch and water pump after that.

Now I have a slide in truck camper that I took along with the trailer and other truck. The truck temp will go from 180 to 240 in about a 1 mile of fairly steep 9% grade and I have to pull over.

What's my problem? Should I dump the 35s and go to stock tires? Do a need a bigger radiator? Am I towing too much? This truck's tow rating is only like 8k with stock tires.
 
How is the shroud?
Tstat?
 
With smaller tires your engine will not work so hard.

Remove the cooler for the trans from the radiator & install an aux. trans cooler.

Like said, check your rad. shroud. You need to be pulling all the air through the radiator you can. You may need to look into a more efficient engine fan.
 
What is the coolant mix?
 
Check for dirt and debris at front of radiator. You may have to loosen radiator or condenser to access. Flush with water and compressed air. Fixed same problem on 01 burb
 
My 2.
33's or really 32's (about stock) would suit 4.10's with a gas 5.9 much better for extreme towing (mountain hills). I might would try 35's if rolling hills / flat land for better fuel mileage...
 
Jeff B said:
With smaller tires your engine will not work so hard.

Remove the cooler for the trans from the radiator & install an aux. trans cooler.

Like said, check your rad. shroud. You need to be pulling all the air through the radiator you can. You may need to look into a more efficient engine fan.
Click to expand...

OP said manual trans, do they run into the radiator too?
 
Some do.
 
That one won't have a cooler. It's an NV4500 and there's no lube pump. I'd drop to a 285/75-16 or about a 32/33" tire.
 
with some rough calculations, your tire size is a big contributor. your current 4.10s and 35s turn close to the same rpms as 3.73 with 32s. to get back into the range, you can either go down to 32s or 33s with your current gears or keep your tires and re-gear to 4.56s and that should put you really close to factory spec for rpms/speed to keep the engine in a better range, allowing it to spin a little freer on long climbs.
 
One missing piece of data.
What speed are you running during this?
What RPM range?

Its a gas motor not a diesel, if you are trying to keep up with the diesels and run 65 mph up those hills you simply need to appply less skinny pedal.
 
My 7.3 4x4 Excursion was doing the same not too long ago. Only getting hot while towing. Just fine without a trailer. Ened up being a slightly clogged radiator that was restricting flow enough to be a factor when working the truck. I also threw a new tstat and housing, fan clutch and fluid in it while I was at it.

I'm not so concerned about tire size though being a diesel. Currently running 33's and stepping up military 37's in just a few weeks.
 
Most of the time on these hills I'm in second running 3500-4000 rpms, which puts me at about 25-30mph. I'm sure the coolant mix has too much water in it - the new water pump had a leak around it I was trying to fix so I had to drain the radiator a couple time and I was only using water. There's no tranny cooler.

I'm thinking of replacing the Tstat and putting in an aftermarket higher flow/capacity radiator. If that doesn't work I'll drop probably to around 31-32" tires.
 
maddog411 said:
Most of the time on these hills I'm in second running 3500-4000 rpms, which puts me at about 25-30mph. I'm sure the coolant mix has too much water in it - the new water pump had a leak around it I was trying to fix so I had to drain the radiator a couple time and I was only using water. There's no tranny cooler. The shroud is fine.

I'm thinking of replacing the Tstat and putting in an aftermarket higher flow/capacity radiator. If that doesn't work I'll drop probably to around 31-32" tires.
Click to expand...
 
The thermostat shouldn't have anything to do with it. So long as it's getting up to operating temperature quickly and staying there, the tstat is working fine.

Clean the radiator, make sure the cap is holding pressure, make sure the fan is working like it should. If your mix is high in water, that will actually have better heat transfer characteristics than a mix of coolant and water. There's the risk of freezing, but it shouldn't be contributing to your cooling issue.

Is the system actually boiling over, or is the gauge just getting high, and you're backing out of it? If you have an infrared thermometer, it might be helpful to verify that the dash gauge is accurately communicating the correct temperature.
 
The red line on the gauge is about 250. At 240 a warning light/bell will come on, and I pull over at that point. I normally leave the truck running, open the hood, and run the engine about 1500 rpm until it cools to 210. It overflows a little bit at this point. If I shut the engine off at 240 it overflows a lot.

Any suggestions on where to get a better radiator instead of just cleaning the existing one?
 
Buy a brand new one for a V10 truck. It won't be clogged and should increase cooling. Brand new 2000 Ram 2500 V10 Manual radiator is $178.79 on rock auto. Or you could call 1-800-radiator and price one there.
 
Are all of the factory air dams in place?
 
Everything Shawn said. Tires also. you can pull the radiator and have it checked, flushed, rodded, and take that out of the equation.
Shroud, air dams, water pump, radiator flow, fan, timing, tire size vs gearing. All can contribute. How many miles on engine/radiator?
 
maddog411 said:
Replaced the fan clutch and water pump after that.
Click to expand...

Might not even be related to your issue, but definitely worth mentioning..... when I first bought my Dodge (diesel) I had overheating problems when towing. After a long, drawn out and frustrating battle I found it was a defective fan clutch. The first two I had bought were defective from the parts store. My parts guy finally ordered a new one for me direct from the factory. It worked fine, and solved the problem. Some of the old timers on here may remember that one. I know John B. does! :)

I suspect the defective ones that I (or someone else) had returned, still appearing to be clean, shiny and still in new-looking condition, were simply put back on the shelf and resold. Don't know that to be fact, but it seemed to be a good theory at the time. :confused:
 
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