Ok I just bought a 24' Toy Hauler trailer and was towing it home yesterday from where I bought it. There is a "mountain" pass on the way home ~35deg grade. The outside temperature was ~105deg F. Running on the flat ground at 60mph my stock temp gauge was showing 190deg. It was straight up and centered. I hit the grade, backed it out of overdrive and was turning 2500rpm at 45-50mph and my temp started to climb. When it swept out of the white area into the space between it and the "red" overheated temp I pulled over, let it idle until the temp came down then continued up over the top of the pass and it was ok after that.

That is not to say if I head to So. CA for a holiday with the family it would not occur again going over the grapevine or any other extended uphill road. So my question is other than:

1. Drain, flush and refill the coolant.

2. Verify the radiator fan turns on.

What can I do to combat this issue?

1996 Dodge 2500 4x4
Automatic trans
207,000 miles
Extended cab long bed

 

I'd make sure the intercooler, radiator, and trans cooler haven't been gooped up by the blowby tube and packed with crud

 

12v trucks don't have a blowby pill/puke bottle problem like the 24vs do. But his radiator still could be plugged up on the outside. And that should be checked.

 

When you say "plugged up on the outside" do you mean just dirt, bugs etc stuck to the front of the radiator?

 

I recently learned,a few tricks while towing thru mountain passes.I was towing about a 8000lb load.If I kept the engine RPM over 2000 and boost over 35ps.before I hit the start of the incline, I could actually accelerate up to 85mph going up the incline, EGTs wouldn't go over 1100deg and engine temps wouldn't go over 200deg. this was in overdrive and lockup, tranny temps would hoover about 130degs. If I let the boost drop below 20psi EGTs would hit over 1200deg and the engine would start to run hotter 220 to 240deg.

 

Living in CA you may not use winter fronts but I remove the top 2 in summer. It makes it run way cooler when towing.

Jim

 

Do you have a trans temp gauge? With the engine temp staning at attention, I'd hate to know what the trans temps were.

 

Just a suggestion - since you have a 12 valve engine, you might want to post this question in the 12 valve versus the 24 valve forum.

In all likelihood, you were pulling the grade with the torque converter unlocked. This generates a lot of heat that is dumped into the radiator tank cooler, driving up coolant temperatures. On my previous 1996 V-10/47RE 3500 dually, I added a B&M Supercooler on the hot line between the transmission and the radiator tank inlet which helped a lot in stop-and-go traffic and on long grades when pulling a 5th wheel. I used this particular cooler because it was one of the few I could find back then that had 1/2" NPT inlet and outlet fittings, and the 47RE uses 1/2" tubing for the cooling lines as opposed to the more common 5/16" or 3/8" tubing that most coolers are plumbed for.

Rusty

 

if your truck has the fog light plastic inserts in your bumper it helps a lot to pull these out so there is more areas for fresh air to pass into the engine bay... my temps dropped about 20 degrees towing just doing this.. didnt relize it or intend to do it... just a mistakenly stumbled on it when one of my plastic peaces were cracked and i just took it out to look better and when i did that i took the bumper brackets off and touched them up with a fresh coat of black paint so it looks clean...

 

I agree 100% with above.
when towing my race car trailer , i found it runs cooler and keeps its MPH when buzzing the motor at 1950-2050 rpms ( sweet spot ) thats about 68-70 mph for me. More boost = cooler EGTs

 

Ok, thanks for the replies! As a note this is the 12v section not the 24v?
I first took it to Jiffy lube and had the radiator drained, flushed and refilled. As well as the full transmission service done. All 17 quarts flushed and replaced as well as the transfer case and front and rear differentials fluid replaced. I towed the toy hauler up the CA 152 grade and it was only marginally better. I was not happy so I looked further. Anyhow my truck has 3 rows of radiators. Between the 2nd and 3rd row I found a ton of dirt, bugs and an inspection mirror. I hosed and hosed with water until I got it all washed away. Other than the inspection mirror, I pulled that out with a hook. As I towed the toy hauler back to the RV storage lot it tentatively ran cooler. I will know next weekend when I go up to Stonyford to ride the dirt bikes towing the toy hauler.

Thanks,

Troy

 

with the age of the truck your radiator could be getting build up inside the tubes when you had it flushed did anyone look in side it to note if all the tubes were clean? also you should hear the fan clutch start to engage and sound like a roaring jet .cant miss the sound you should have plenty of cooling with the system in top notch shape. also make sure the trans cooler is clean or that extra heat gos to the cooling system.A worn trans also make more heat. just my .02