charger 69

I don't know what 350 HP. feels like but I know what 160 did. The mods I did helped consiiderably but what I am looking for is to be able to pull my GN (I am guessing 10-12K and what ever sized 5ER I get) and be able to do hills without the engine temp.flying past 220* when the weather is HOT like 90* or more. My guess is that I am going to have to replace the stock radiator with the largest-thickest one I can put in it to handle the extra HP. EGT I can control with my foot but I have to pull hills in second gear so as not to melt the engine. Even on the flat I can't tow in OD because as soon as I hit the button every temperature goes up. At 70* heat is not an issue and I can run in OD. When towing it runs a solid 10 MPG.so it has got to be burning a lot of fuel and producing heat. Am I missing something or is it time for a radiator?? I think it will look kind of funny with a Frieghtliner radiator wire tied to the grill.

MikeThomas

Hmm, you should have the cross flow radiator...plenty good. Do you have the factory temp gauge or an aftermarket? The factory ones just arent accurate to go by.

charger 69

Both and they don't agree most of the time. The second gage is mechanical and i have seen the stock gage pegged and the other at 230*

Boatnik

I am officialy old so bare with me. I need to ask what type coolant are you running. Too much anti freeze is just as bad as not enough. A 50:50 mix of ethelyene glycol has a good heat transfer coefiecent. the new long lasting or environmentally safe antifreeze are not quite as efficient.

Next question: Do you hear the fan kick in when it gets hot? If not the fan clutch hub may need attention.

charger 69

coolant is the old green stuff but I am not sure of the mix ratio (the truck came from AZ.) and yes the fan comes on with a roar of air when it does. The coolant doesn't empty itself out,I don't have to refill it and there hasen't been any sign of it in the oil that I have seen.

Boatnik

Anything that you can do to reduce heat load will help. I read here that there was a dealer option for mounting a trans cooler on the skid pan frame too reduce the amount of heat in the tranny. It was a tranny cooler mounted between the brackets with an electric fan blowing down through the cooler.

charger 69

I've got one already.The trans. temp. would peg at 250* instantly before,now it rairly hits 230* even on hills. I've thought about putting another cooler in the line that goes to the heater core and the heat exchanger and mounting it in a 6pack hood scoop to see if that would help.

wannadiesel

How old is the radiator?

nweaver916

My 93 was overheating (should be able to find the thread) and I put a huge underbed cooler between the tranny and the heat exchanger on the engine. It helped a ton, I pulled about 6K of horses/trailer. I slowed to 55 to pop it out of overdrive (don't want to overheat, like to keep it cool) going up the hills, but downhills/flats it's OD on and 65 without a hitch. make sure you put the additional cooler between the tranny and the exchanger on the side of the engine.

timb

One thing that eluded me when my truck was having over heating problems was the fins on the ac condensor were all flattened of from whacking bugs for several years. pulled it out, and no more ac or over heating.

charger 69

Original I would think.Its probably never been out of the truck.

Thomtek5

I want to see the Freightliner mod

wannadiesel

That's likely your problem. Even if the inside is clean, chances are the fins are rotted out and not pulling heat away from the tubes.

DBF

What Wanna said.

These things just weren't designed to tow 12,000 - 14,000 pounds in that kind of heat.

Another trick - put the cheap mod 3200 rpm spring in the pump. Running in OD doesn't send as much fluid out to the coolers as running in 3rd/direct. With the 3200 rpm spring, you can run up over 65/70/75 depending on how big a wall you're towing down the road. It's loud, but it'll be cooler than OD and not a big mileage loss.

Regards, DBF

throttleking

I feel your pain. I just got back from PA towing 7,000lbs and I noticed 2 things while towing in 90 degree heat. While driving 70 mph trying to keep up with I-95 traffic in overdrive the trans never runs cooler than 210 degrees, if accelerating for any type of grade or to pass it will hit 230. Out of overdrive the temps are between 180 and 200, but rpms are 2500-2800 and the engine starts running warmer than normal. I can feel the heat off the floorboards. EGT's are cooler in drive also. All of this heat generated and I didn't even run the air conditioning! I have a crossflow radiator that is only a year old and I run dexcool (orange antifreeze). At 65mph or lower the temps are normal. The truck just wasn't built to tow at 70mph. I am trying to figure a way around it though. I think the auto trans is what is holding us back. I am going to try and run amsoil in it and see what happens.