Over heating while towing.

[Lubbockguy1979]

So truck is a 16 cclwb 4x4 srw f350. 3.55 gears. Running 295/65/20 tires. Truck has almost 49k. I had a issue where it got warm and blew coolant at 4th of july. Towing a 39.5ft 14ft tall toyhauler. We were traveling at night to avoid 100±⁰ days then. I blew it off then as a fluke. Truck didnt miss a beat or get ”hot" on the gauge but was close. Fast forward to thursday we packed up to head to Colorado. Again traveling in the evening. Trailer is likely at a solid 16-17k and should be within the trucks factory " spec". Pulling hills you can watch the temp gauge climb. Ive been locking put 6th gear and began locking out 5th. Oil temps got to 248⁰ tranny was like 190⁰.... Seems like the issue is on the secondary cooling system. The fan does kick on truck is also running tyrant tow tune. Im not trying to run 70+mph. We are talking 40-50 climbing hills which are fairly steep. Just never had a problem out of this truck. When we get home i plan to replace the coolant in both systems as its time plus ive diluted them by topping off the secondary. But what do i need to look at. Looks like its blowing it at the cap and im backing off alot on hills to keep temps down on my way home

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[webb06]

So truck is a 16 cclwb 4x4 srw f350. 3.55 gears. Running 295/65/20 tires. Truck has almost 49k. I had a issue where it got warm and blew coolant at 4th of july. Towing a 39.5ft 14ft tall toyhauler. We were traveling at night to avoid 100±⁰ days then. I blew it off then as a fluke. Truck didnt miss a beat or get ”hot" on the gauge but was close. Fast forward to thursday we packed up to head to Colorado. Again traveling in the evening. Trailer is likely at a solid 16-17k and should be within the trucks factory " spec". Pulling hills you can watch the temp gauge climb. Ive been locking put 6th gear and began locking out 5th. Oil temps got to 248⁰ tranny was like 190⁰.... Seems like the issue is on the secondary cooling system. The fan does kick on truck is also running tyrant tow tune. Im not trying to run 70+mph. We are talking 40-50 climbing hills which are fairly steep. Just never had a problem out of this truck. When we get home i plan to replace the coolant in both systems as its time plus ive diluted them by topping off the secondary. But what do i need to look at. Looks like its blowing it at the cap and im backing off alot on hills to keep temps down on my way home

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Don’t think the secondary system is the issue if trans is only 190.

Maybe check and see if the front of the primary rad is plugged with grass seed, bugs, hay, etc. don’t know if it’s a farm truck or anything like that.

What was coolant temp when oil was 248? Maybe worth throwing a thermostat at it?


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[6.0 Tech]

Our tow truck does this too, once oil temp hits 245 the coolant gauge starts to creep, and by 250 or so on the oil it’s at hot. Once it starts creeping, I typically slow down. Some of the steep hills around us I end up doing 30ish. It happened with our retrofitted 11 250, and our stock turbo 16 450. I’m guessing our trailer with the 250 was around 15-17k loaded, our new one is probably closer to 20k.


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[Lubbockguy1979]

I visually looked at the radiators about a week ago when i had the grill off messing with lights. It did not look too bad. Truck is primarily our road trip vehicle and run around town when im not in one of my work trucks. The coolant reservoir to the front is the one i thought was the secondary and the one ive topped off a few times. Unfortunately the gauge cluster does not tell coolant temp just oil and trans temp. I didnt have a monitor on it to know coolant temp. It is almost like the gearing is too high. Truck seems to do alot batter 70+ vs 55-65mph. Just an observation of the trip home from Colorado to texas. On flat ground no issues. Even small hills no issues. Give it a decent climb and yeah temps climb

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[Lubbockguy1979]

Our tow truck does this too, once oil temp hits 245 the coolant gauge starts to creep, and by 250 or so on the oil it’s at hot. Once it starts creeping, I typically slow down. Some of the steep hills around us I end up doing 30ish. It happened with our retrofitted 11 250, and our stock turbo 16 450. I’m guessing our trailer with the 250 was around 15-17k loaded, our new one is probably closer to 20k.


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Nice to know im not the only one having the issue. Im guessing i need to replace the thermostats in the secondary possibly?

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[6.0 Tech]

Nice to know im not the only one having the issue. Im guessing i need to replace the thermostats in the secondary possibly?

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We just live with the temps on our truck.

As for the puking on yours, is it stock? I’ve seen quite a few intercoolers leak, and cause the puking from the secondary. I also have some sort of theory on loss of coolant capacity due to that bog ass thing on the passenger valve cover falling off causing overheating of the coolant in the secondary and boiling over.

Secondary thermostats probably will not fix anything, but they’re cheap enough and easy enough to do probably wouldn’t hurt anything. My thought is it seems to be the primary getting hot, as the oil is getting up pretty high.


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[TrickTruck]

Did you ever resolve this??

This is how we roll. w/ the Maverick in the back and a full load of water and all our crap, we gross at 25klbs on the CAT scales.
Truck details in my sig, but it's been on the diet plan and runs Chaos SOTF tunes.
Towed this piglet from SC up to IN, and then on to NY (Erie/Buffalo area), then back home last summer and it was hot as blazes most of the way. Roughly 2500mi.

Truck pulled like a champ.

I did find that putting it in manual 5th was the best combo of power and mpg (10-10.5mpg avg) on almost all terrain. Even locking out a gear in auto didn't do it for me. It would start to load up, then just as it was really getting work done it'd drop to 4th, revs would go up and the EGT's would climb. I found that locking it in 5th and letting her eat gave the best results.
I'd say it's biggest challenge was some of the steeper and longer passes where it really needed to be dropped into 4th and spinning some higher RPM, then EGT's would get hotter than I liked and even switching to a lower tune level on the SOTF didn't bring them down enough.
When EGTs did climb, just slow down a bit from a normal of 70-75mph to something in the low 60s and it was fine.

It's definitely not something that's doesn't need monitoring tho. It's a driver's rig, not to be ignored. The bumper pull / sway keeps me on my toes anyway - but that's another subject.

Water Temp gauge never moved, trans stayed right at 200° and oil would get no higher than 235-240°.
I know, passes in these areas are nothing like out West, but still, easy 100°F days and we never slowed down as long as the EGT's held out.

All this is to say that IMHO something is abnormal in your situation. Your truck should not be overheating.