Sparksalot
Elite Member
287 is a pleasant drive.
Keeping coolant and transmission temps under control when towing in the summer heat
- Thread starter Geotrash
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Alright, well we made it to Rock Springs. It was a brutal trip. Roads were torn up in places and we had wind gusts up to 60MPH (gotta love WY) and a sustained wind of 25MPH. I can for sure say the Denali does not like thin non dense air, and hot air (it was 83-90 all day till dusk). Pulling the small trailer up to Genessee Park spiked temps like normal. It’s a gnarly little hill and give anything a workout. Driving up I25 North with the trailer wasn’t horrible. There was tons of construction and idiots to go around. We did take 287 because I hate the drive from Cheyenne to Laramie. There are a few good pulls going that way and I ended up with trans temps in the 220’s. Wasn’t there for long but also didn’t want to stay cool. Then came the shit show. West to East ish winds from before Laramie all the way to Rock springs. 3 gear was my best friend and we averaged 55-70MPH. Once the outside temp dropped below 70 the coolant temp didn’t budge and the trans stayed under 203. I kept the RPMs under 4K. This damn thing has 177K so it’s not enjoying it. I also believe I blew out my shock seal at some point because the fron left control arms and wheel and stuff had a oily fluid all over them when we got to Laramie. There was a few nasty bumps on 287 and one may have taken it out.
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OP
OP
Wow. Thanks for taking the time to post after such a long day. Sweet little camper you rented there, too, and it looks like the WDH is set up well for your truck.
I spent some years working on drilling rigs around Wamsutter and the Red Desert area along I-80 west of Rawlins, and I can confirm that the wind there is constant - even in the winter. I've seen some catastrophic mechanical failures in cars/trucks along that road, and helped a few stranded families get back on their way. The headwinds are enough to push any vehicles that are on the mechanical edge, right over it. The only mercy is that at nearly 8000' for most of the way, it's seldom very hot. 287 is always windy also - crosswinds. Today, I imagine you'll head up through Farson and Pinedale, along the wind River Range. Some beautiful country, for sure.
It's super helpful to me to know what you were getting for temps along the way, so thank you for taking the time to post. On the shock seal failure - did you get a chance to look under the hood and confirm the source? I only ask because those oil cooler lines run right past that area and are notorious leakers, as I'm sure you know.
Oh nice. Yeah I worked up here a lot when I was with UPRR. I checked the oil cooler lines and the fluid was not consistent with engine oil. It felt like power steering fluid or what I’d assume was shock fluid. I’m gunna take the rig through a do it yourself car wash and get it all cleaned off and maybe today I can pin point the issue. BTW after living closer to sea level and having 93 octane I can officially say I hate 91 and altitude…….
OP
OP
Yeah, it's a double-edged sword for sure. A normally-aspirated engine loses about 3% of its horsepower for every 1,000' above sea level, and warmer air only makes it worse. So driving I-80 across southern WY, you were down on power somewhere around 21-25%. 91 Octane is all that engine can really use given the reduced air density in the cylinders. At the same time though, making less power means there's less work for the cooling system to do. The downside is having to hold 3rd gear just to keep going. I'd rather have the power and figure ways to keep it cool! Hmmmm... may be time for a supercharger. Lol.
mikeyss
Full Access Member
I took my Tahoe up a long mountain road today, through Ward and up to Estes... Drove it hard and saw my trans hit 180 with my Tru cool. It was about 80 out, engine temps stayed normal.
ddann19
Member
I’m leaving Illinois for Smith Mountain Lake on Sunday!
That’s great. So the biggest difference is we are all aluminum block and heads in the 6.2 whereas the Tahoe has the 5.3 which is an iron block. The iron block takes a long time to heat up compared to the all aluminum setup we have.
Alright so today went much better. 1st there was no wind!! Yay!!!!! Second the road was nice and gradual the whole way to Jackson. Trans temps never went above 200 and the coolant never saw over 215. I held 4 gear almost the whole way and sometimes ran in 5th. 3rd was necessary for a few long climbs but it wasn’t like the day before. So needless to say wind blows…….
I definitely recommend a aftermarket cooler. Also if you can find a good mounting spot for something bigger than the 30 row I purchased it wouldn’t hurt.
I definitely recommend a aftermarket cooler. Also if you can find a good mounting spot for something bigger than the 30 row I purchased it wouldn’t hurt.
OP
OP
No wind on that drive? Better go get yourself a lottery ticket!
Where will y'all be camping in that area? We reserved a spot for a few nights at Colter Bay and another few nights in West Yellowstone at a place called Yellowstone Holiday Resort. Glad your temps stayed under control for the trip. Maybe I should've investigated the American Volt coolers also. 30 row with a fan sounds just about perfect and I like that they offer thermostats with different ranges.Side note: I think most of us on this thread running a Derale have the 13960, which is a 25-row cooler and is spec'd as having slightly more cooling capacity (46,000 BTUs with the fan running) than the Tru-cool 40K (45,000 BTUs). If anyone is interested, the next size up is the 40-row 13870. It still has the 6AN fittings but is another 3.5" taller and offers about 50% more cooling capacity. It would definitely hang down further than I would like, so I think with dropping the license plate down and opening up that lower grille fully, I'll finally have the cooling where I want it to be with the 25-row. The way mine was set up before hidden behind the license plate it was operating in a relative vacuum. Now I'll have the benefit of the ram air effect.
I prefer the Derale over the Tru-cool because instead of running at full cooling capacity all the time like the Tru-cool (passive), the Derale only runs at full capacity when the fan is running (active). That gives the transmission fluid the chance to get up to the minimum that GM specs for this transmission (150ºF) year-round.
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Lol right!! Seriously though it was great.No wind on that drive? Better go get yourself a lottery ticket!
Side note: I think most of us on this thread running a Derale have the 13960, which is a 25-row cooler and is spec'd as having slightly more cooling capacity (46,000 BTUs with the fan running) than the Tru-cool 40K (45,000 BTUs). If anyone is interested, the next size up is the 40-row 13870. It still has the 6AN fittings but is another 3.5" taller and offers about 50% more cooling capacity. It would definitely hang down further than I would like, so I think with dropping the license plate down and opening up that lower grille fully, I'll finally have the cooling where I want it to be with the 25-row. The way mine was set up before hidden behind the license plate it was operating in a relative vacuum. Now I'll have the benefit of the ram air effect.
I prefer the Derale over the Tru-cool because instead of running at full cooling capacity all the time like the Tru-cool (passive), the Derale only runs at full capacity when the fan is running (active). That gives the transmission fluid the chance to get up to the minimum that GM specs for this transmission (150ºF) year-round.
Our first three nights are at The Virginian RV Park in Jackson. The Monday we head to Colter bay for 2 nights, then Buffalo fireside or something like that for two night and then Grant campground for 4 nights.
the only time I’ve been unhappy with my trans temps was during the wind issues. But honestly nothing except an HD cooling system helps you there.
I investigated the leak in the front driver corner just a little and it seems that it is fluid like power steering, brake, or shock fluid.
also I started getting a little oil burn at startup. However my last fill up the 91 octane had 0% ethanol in it so that may be a slight contributor to the smoke at startup? Either way I think after 178K miles and a life of towing it may be time to rebuild the ol 6.2.
OP
OP
A little blue smoke at startup is a telltale sign for valve stem seals. After 12-13 years, it makes sense that they’d be getting a little hard/worn. Easily replaced in an afternoon. If the engine is making good power and you’re not burning significant oil between changes, the bottom end should be fine. I haven’t seen a 6.2 needing rings yet, except those with stuck rings from the oil bypass not having a deflector or PCV-related issues from the older valve cover design.
OP
OP
Replaced the baffles beside the radiator this week with black coroplast, zip ties and some rubber hose to protect the A/C piping. Hopefully it will help with cooling effectiveness. Heading over the blue ridge again tomorrow afternoon with the camper with a full water tank for boondocking, and it's gonna be warm. We'll see if the new setup makes any difference to transmission temps. I'll report back here with the results.
Sparksalot
Elite Member
Between the bafffles I made and ensuring both fans were running, mine stayed very nicely cool on my last trip.
kbuskill
***CAUTION*** I do my own stunts!
I am definitely interested in how much of a difference this makes.
Mine have been MIA for a while, but I don't really do any towing.
I have a decent sized external transmission cooler I put on the Burb to replace the factory Auxiliary cooler but it isn't as big as a 40k...
You can see it is the black one in the center, not the silver one on the passenger side.
My transmission, once up to operating temperature, runs consistently 80° above ambient temperature.
mikeyss
Full Access Member
This was driving around in the city yesterday. This is still like 40 degrees cooler than last year when I had the stock setup.
Minus the dangling cooler tube, this is my setup. I have the big Mishimoto radiator too. The one difference with my new setup is my engine cooling fans run on hi a LOT more, which I don't mind. I have dual batteries and K5L fans, the voltage stays at 14V most the time. I'm keeping my fingers crossed I won't run in to any hot issues.
Minus the dangling cooler tube, this is my setup. I have the big Mishimoto radiator too. The one difference with my new setup is my engine cooling fans run on hi a LOT more, which I don't mind. I have dual batteries and K5L fans, the voltage stays at 14V most the time. I'm keeping my fingers crossed I won't run in to any hot issues.
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Sweet man. I am looking forward to hearing about your trip. Not much has changed here. I did fill back up with 91 with 10% ethanol and now I don’t see smoke. I had to remind myself that the ethanol was added to help vehicle burn cleaner and since the last tank was non ethanol and I don’t have any cats, then any time I feed fuel to the motor it’s gunna dirty burn and there’s nothing to make it clean. Either way if I have to rebuild it then I have to rebuild it. I also may start the process of getting a duraburb from duramax specialties.
I made a 500 mile trip on Sunday, I have the tru-cool mounted in front of the radiator as pictured above, since my transmission was rebuilt with extra clutches and etc, it seems to run a bit warmer than it used to, at 7-8000ft elevation and 90deg's ambient, ac going and moving at about 75-80mph transmission heated up to 193, that was not the issue, the issue is this made the coolant heat up to 230deg. turning the ac off seemed to help a smidge and coolant temps were then up and down to around 220-225, so I am planning on moving the tru-cool down to the bottom grill and doing like others have and opening up the lower grill holes, just have to figure out some kind of mount. not sure how much air flow it will get at that lower grill or if will effect any other cooling I am thinking probably not because the lower part is below the center of the bumper cover that should be splitting the air 50/50? up/down
mikeyss
Full Access Member
I wonder if the grill opening between the Yukon and Tahoe cause some of this air flow issue. I was above Estes Park the other day with outside temps in the 80's and my trans saw 180 with very aggressive driving up the mountain, and the engine temp never budged off the normal straight up on the gauge. I pay close attention to you guys experiences and am trying to duplicate any hot conditions in case I need to move mine. I go MILES off-road here in Colorado and want to be certain I won't overheat.
I don't know it only has become a issue for me at high altitude/high desert and warm outside, putting around at sea level it's never been a problem
I went up to Yerrington which is a valley but still high desert it didn't like the hot high altitude it was 104 up there I didn't have to slow down or anything it just made it concerning.
i think if I move the tru cool that should resolve the problem, either move it to the bottom or maybe flip it sideways and to the side as much as I can.
and of course were having a big heatwave right now I don't want to even mess with it.
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