Engine temperature while towing

I guess I'm old school, but I had always been taught that if the temperature gauge moves up towards hot, you pull off and let it cool down. I'm pulling a 32' Keystone Cougar X-Lite that is 6700 lbs empty so around 7500 lbs loaded in Pa. I had been pulling with a 98 Dodge Ram quad cab with a 318 and 3.73 gears and it was a all it could do. The maximum towing on it was 7800 lbs. I just got a 2006 Sierra 1500HD with the 6.0 engine in it and 3.73 gears. Pulling up a mountain at 65-70 mph in central Pa about two weeks ago, I noticed that the temperature gauge started at normal operating at just under the 200 degree mark; 260 is red hot on the gauge. The temperature went up to around 225 -230 and I didn't expect it to move much. I'm a bit worried because later this year we will be towing up the I76 turnpike towards Pittsburgh where the tunnel is. With my old truck I had to pull over and let it cool about 2/3 of the way up the hill (or did I?). I got the 1500HD to make sure I'd be able to tow the camper where I wanted to tow it, but now I'm afraid it might get too hot going up the mountain especially if it's hot outside.

I have a buddy who has a 2002 Silverado 2500HD with a 496 big block (8 litre) in it (only 40,000 miles and immaculate yet). He tows a 8400 lb camper that is about 9500 lbs loaded. He said that even with that truck it heats up on mountains, but has never once over-heated. He says it will go all the way up to red on big mountains, but doesn't ever overheat so he was saying not to worry about it because it can handle it.

I'm a bit worried about letting the gauge go that high to see if it can do it and not overheat. What are the experiences of those here? Is it normal to expect the gauge to go up near red and should I not worry about it? My tendency is to let it get up to maybe 240 and then pull off and let it cool down. I know turning off A/C and even turning on the heater can help so I'll turn off the A/C as a first step. Thoughts?

Ron3rd
Explorer III
Jun 12, 2014
My experience is my temps never move, towing or not, going up a hill or not. Maybe the gauge is broke. My trans temp gauge never moves either.
Jack_Diane_Free
Explorer
Jun 12, 2014
Also my temps stay constant whether towing or not, up hills or down.
Campfire_Time
Explorer
Jun 12, 2014
Your temp gauge should move. Engine temps vary constantly with conditions and load. So long as its not over heating and the temp drops to normal when not under stress you are fine.

Some temp gauges are just pretty front ends that replace the old dummy lights. They have 3 settings. Cold, just right, or over heating. They trick you into thinking they are real time because the needle moves as it warms up. Because they are really just dummy lights, they look like they never change. Its why a lot of people put real gauges on the "A" pillar. Hook up a scan tool that reads temperature and you'll see what's really happening.
Mvander
Explorer
Jun 12, 2014
Try some "water wetter". If heard of people having good results getting coolant temps down a bit.
caberto
Explorer
Jun 12, 2014
Check your manual. It specifically says your truck will give you a warning when the engine temp reaches 250, and when your tranny temp reaches 260 - this is for any of the GM trucks, as this manual is not model specific. It goes on to say it is normal to see temps reach close to those numbers while towing uphill. The tranny and/or engine will warn you first and if it goes beyond those temps will go into a sort of protective limp mode before it will let the engine get damaged, and the DIC display will indicate to pull over and let engine idle until it cools down.

I recently pulled over I-70 in Colorado on a 7% hill for several miles towing our 12K lbs fiver with a 2005 Duramax, and my temps got to around 230/235 on both engine and tranny, but they held there until I reached the top of the hill. I was only doing about 37mph for a good part of the hill, but I didn't want to force the truck to try and go faster and get hotter. That's an extreme hill and extreme distance pulling a heavy and large profile trailer, and most people won't come across that type of hill very often. We have a lot of hills here in California, but I had never towed up one that steep for that long, so yea, I was sweating a bit, but after I checked the manual and did some more reading from other owners, I found those temps are not unheard of.

I know you don't have the Duramax, but the manual (non-engine or truck specific) does indicate that at those temps (250 engine and 265 tranny) will give you a warning. So at 230/235 you're still good, as long it appears to hold there or get cooler after the clutch fan comes on (if your truck has one).
tdouty
Explorer
Jun 12, 2014
I did notice that when it got to around 230 it stayed there or began dropping off. This clutch fan you mention ... what is it and about when would it come on?
caberto
Explorer
Jun 12, 2014
If it stayed or dropped off when you reach around 230, then it sounds like your truck's cooling system is working properly.

The fan clutch comes on when the temp reaches 230. You can hear it, it's your regular fan but spinning much faster, and there's no mistaking that it is on as it is pretty loud. I'm not sure if your particular engine comes equipped with the fan clutch or not.

Also, if you have the tow/haul mode in your truck, be sure and use that when towing; it will help keep the tranny locked in gear so it's not hunting back and forth for the right gear and get overheated.
Tystevens
Explorer
Jun 12, 2014
tdouty wrote:
I did notice that when it got to around 230 it stayed there or began dropping off. This clutch fan you mention ... what is it and about when would it come on?

Yep, that's about when it would kick. All of my trucks have shown a bit of an increase on a long hard pull, the aux fan would kick on when the gauge shows about 230*, and the temps would immediately stop climbing and usually head back down. Sounds like everything is working fine.

I'm surprised you didn't hear the fan kick in, though -- on my Duramax, it sounded like a plane about ready to take off. I guess is isn't as noticeable on my gasser because the engine is already running at high rpm.

You may be old school, but these trucks are not. It is pretty hard to damage them if everything is working correctly.

Good luck!
Bull_Rider
Explorer
Jun 12, 2014
I agree, your temp. gauge will increase on a hard pull. At around 220-230 I can hear the engine fan kick on, and the temps. come down. It takes a pretty good hill to make the fan come on, but it's not uncommon, nor should it be a concern.

When we head down the other side, the temps start dropping until the thermostat starts to close off to keep the temps in the proper range.

If the fan kicks on, the the temps. continue to increase, then I'd start to be concerned.
ChooChooMan74
Explorer
Jun 12, 2014
Slowing down will need less power which means less heat and better fuel economy, lower tire temps, and less chance of a blowout.