2007.5 LMM Engine temp Towing in Mountains... clutch??

[ff43sc]

This past summer i towed a 30ft 9000lb camper(very tall) through West virginia Mountains, I had my cruise control set at 70MPH with tow/haul on. It was about 90-95 degrees that day but a few times in the steepest grades, while the truck didn't seem to even notice the load I was pulling, the Engine temp got up to approx 240-250 on the temp gauge, and i didn't notice the fan clutch kicking in. I turned off cruise and dropped speed to 55-60 until the temp dropped back down each time this happened.

I mentioned this to a local GM dealer when i had truck serviced recently, and all the service writer would say was Everything was working as designed in the cooling system/sensor, etc. And that maybe i should consider what i was trying to tow and not tow such a heavy trailer. I advised him the truck's rated to town 13,500 so I didn't think 9000lb was exceeding what the truck was rated to pull and he again said maybe i should haul a lighter trailer...

Any one else have similar problems like this? i previously had a 6.5L and would notice the clutch kicking in every time...
Should i find another dealer, or should i see the gauge approaching 260.....during this run, the trans temp was running around 210-215max...
thanks.

[richp]

Hi,

I can't tell you whether to find another dealer or not. But I can tell you that my LMM has pulled a 12,000#, 34' fifth wheel with a very high profile all over the country. That includes numerous pulls over the I-70 passes in Colorado over the Rockies, in and out of Death Valley, and lots of other long, hot pulls.

I've never seen temperatures like that, and I also haven't noticed the fan kicking in that often. (In fact, I have the opposite thing happen -- my fan sometimes kicks in on a cool morning when there is absolutely no reason to need any extra air flow at all.) But I confess that I don't quite go as fast as you. I set the cruise on 65, and can go all day and not worry one bit.

FWIW.

[JohnC]

(In fact, I have the opposite thing happen -- my fan sometimes kicks in on a cool morning when there is absolutely no reason to need any extra air flow at all.)

That's normal. The oil in the clutch hub puddles up in cold weather and causes the clutch to engage until it gets redistributed.

[ff43sc]

Rich, thanks for the reply, my trailer is a 5th wheel also, I too only hear the fan kick in when its cool out when i first start on the road...when my truck gets warmed up, the temperature sits at 210 hardly ever moves......basically never gets above that except that trip through the mountains. Did you leave your cruise engaged through the mountains? thanks. Also I was showing 10+mpg at 70mph.....

[Mark Rinker]

Too fast for load and conidtions...there is a big difference between 62mph and 70mph when it comes to heat handling with these trucks
Cruise control not advisable for grades. Your right foot is your best method for accelerating as terrain allows, feathering and dropping speed as grade demands.Slow down, use your eyes and foot to smooth out the fuel delivery. You'll get better mileage AND run much cooler.

[ff43sc]

Just pulled a trailer to myrtle beach, on the highway with cruise on @ 60-65mph 90% temp outside, trans temp was around 200 on average. off highway on 55-60 mph roads, trans temp 205-215...that's taking off easy...not stop and go traffic..is this too hot, I had put on here before I wondered if the clutch is kicking in like it's supposed to. that seems too hot for me...engine always goes to 210 once it's warmed up and stays there, but again limited towing with this truck. thanks for any info.

[richp]

Hi,

Noticed this post, re-read the entire thing, and see that I never responded to your embedded question about how I tow. But someone else more or less answered it anyway -- I never use cruise in the mountains, even on the interstates.

If you're towing a fifth wheel with a lot of frontal area, the temperatures you mention in your last post don't seem worrisome to me. Others with more experience likely will chime in here, but it seems to me that if there was a clutch problem you would have had other indications by now.

FWIW.