Keeping coolant and transmission temps under control when towing in the summer heat

[Geotrash]

Hi All, the 2012 XL Denali is a towing beast, but after the cam upgrade, new HD torque converter, and adding the Tru-Cool 40K in front of the radiator, the engine itself is running warm now that we're getting into spring. Hauled our 6500 lb camper down to Virginia Beach this weekend in 83º ambient weather, and the engine coolant temps were running between 227º and 237ºF per the OBD2 stream most of the way, which translates to about 3/4 up the temp gauge on the dash. But that was only at speed... at idle in traffic it was running much cooler, around 205º. So that tells me that my fans are working fine (verified as well), but that the Tru-Cool cooler is likely robbing some of my radiator's capacity when the engine's working hard. Transmission stayed nice and cool the whole way, never getting above 180º.

After reading a bunch of posts from all of you, especially @kbuskill's experience with his Cold Case, I went with a GMT569A as I have oil coolers on both ends of my factory radiator. I like the fact that it's a 2-row with 1-1/4" wide tubes and is significantly deeper than the factory radiator. Hoping that this upgrade will finally make this truck what I want it to be for our summer camping season, including a 4000 mile trip west out to Yellowstone.

Anything else you guys can think of to shore this truck up for camper duty?

 

[HD_LS]

Make sure you put a restriction in the small hose that goes from the top passenger side of the radiator to the surge tank. Otherwise you will get error messages. Including false hot engine, AC disabled actions. The stock radiator hose outlet is restricted, the cold case one is not.

 

[Geotrash]

Make sure you put a restriction in the small hose that goes from the top passenger side of the radiator to the surge tank. Otherwise you will get error messages. Including false hot engine, AC disabled actions. The stock radiator hose outlet is restricted, the cold case one is not.

Thanks D - yes, I did see that in Ken's thread. Thanks for calling it out to make sure - good call.

 

[kbuskill]

Thanks D - yes, I did see that in Ken's thread. Thanks for calling it out to make sure - good call.

Do you have any old aluminum valve stemmed TPMS sensors laying around?

I hear they work great as a restrictor for that radiator... lol

 

[Geotrash]

Do you have any old aluminum valve stemmed TPMS sensors laying around?

I hear they work great as a restrictor for that radiator... lol

So I hear! [emoji6]


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[thompsoj22]

Hi All, the 2012 XL Denali is a towing beast, but after the cam upgrade, new HD torque converter, and adding the Tru-Cool 40K in front of the radiator, the engine itself is running warm now that we're getting into spring. Hauled our 6500 lb camper down to Virginia Beach this weekend in 83º ambient weather, and the engine coolant temps were running between 227º as 237ºF per the OBD2 stream most of the way, which translates to about 3/4 up the temp gauge on the dash. But that was only at speed... at idle in traffic it was running much cooler, around 205º. So that tells me that my fans are working fine (verified as well), but that the Tru-Cool cooler is likely robbing some of my radiator's capacity when the engine's working hard. Transmission stayed nice and cool the whole way, never getting above 180º.

After reading a bunch of posts from all of you, especially @kbuskill's experience with his Cold Case, I went with a GMT569A as I have oil coolers on both ends of my factory radiator. I like the fact that it's a 2-row with 1-1/4" wide tubes and is significantly deeper than the factory radiator. Hoping that this upgrade will finally make this truck what I want it to be for our summer camping season, including a 4000 mile trip west out to Yellowstone.

Anything else you guys can think of to shore this truck up for camper duty?

Try the 700 watt/7 blade fan motor on the drivers side only, It made a difference for me. I know you have skills from reading your posts so consider the additional current required to use it. JMO, But there is no reason to run the trans fluid through the radiator in the summer, When you install the new radiator simply use your trukool as a standalone and id guess you will notice a significant improvement in coolant temps.

 

[Geotrash]

Thank you, @thompsoj22 . I notice that the 700w fan motor may have been standard equipment in the Escalade. But the only place I can find them this morning is on eBay. Any chance you have a source you would recommend? I now also understand the wisdom of your remote mounted Derale cooler.

Update: After a little more research, it looks like the 700W fan motors came with the enhanced cooling package (K5L), which mine does not have. PartsGeek Part Number: 127975-05620229. I'll order the one for the drivers side today and replace it when I pull the fans to replace the radiator. Do you happen to know if the existing wiring will support 2 of the 700W fans?

 

[1BADI5]

Install pics or it never happened

 

[thompsoj22]

Thank you, @thompsoj22 . I notice that the 700w fan motor may have been standard equipment in the Escalade. But the only place I can find them this morning is on eBay. Any chance you have a source you would recommend? I now also understand the wisdom of your remote mounted Derale cooler.

Update: After a little more research, it looks like the 700W fan motors came with the enhanced cooling package (K5L), which mine does not have. PartsGeek Part Number: 127975-05620229. I'll order the one for the drivers side today and replace it when I pull the fans to replace the radiator. Do you happen to know if the existing wiring will support 2 of the 700W fans?

I have had no problem with the harness but i cant claim knowledge of the OEM harness limitations in regard to amperage/current. The 700 watt motor's that i purchased from rockauto are GM#15780796 or ACDELCO#15-80881. I honestly dont advise two 700's. It is overkill, and "unnecessary" except in extreme "short duration" situations. Staying with the 5 blade/500 watt on the passenger side and upgrading to the 7 blade/700 watt on the drivers side is the right combo. Order the new 7 blade fan at the same time, Im serious when the 700 cycle's to high the sound and volume of air will amaze you! You dont want an old brittle plastic fan on the 700 watt motor coming apart and going through your new radiator.

 

[Geotrash]

Again, thank you. After studying all the part numbers for various model years and cooling system options, I landed on a 700 W motor designed for the enhanced cooling system spec (K5L) for the 2012 MY, along with an upgraded five bladed fan designed for the same enhanced system.


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[mikeyss]

Again, thank you. After studying all the part numbers for various model years and cooling system options, I landed on a 700 W motor designed for the enhanced cooling system spec (K5L) for the 2012 MY, along with an upgraded five bladed fan designed for the same enhanced system.


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Yes, for 2012 the fan design changed from a rimmed style blade, to just dual 5 blade with no rim around the blade. The non K5L in 2012 had dual 5 blade assembly with 500 W motors, and the K5L ones still had dual 5 blade but with 700 W motors, and I think the fans were a little larger. The older designs from 07-2010 had the 5/7 or 7/9 rimmed blade design, with 500 W or 700 W. It got confusing with all the different options for fans. Lol

 

[Geotrash]

Yes, for 2012 the fan design changed from a rimmed style blade, to just dual 5 blade with no rim around the blade. The non K5L in 2012 had dual 5 blade assembly with 500 W motors, and the K5L ones still had dual 5 blade but with 700 W motors, and I think the fans were a little larger. The older designs from 07-2010 had the 5/7 or 7/9 rimmed blade design, with 500 W or 700 W. It got confusing with all the different options for fans. Lol

Thanks for validating, Mike! Glad this info from all of us is here for future folks attempting the same job.

 

[Geotrash]

Just an update here. I towed our 6500 lb camper over the mountains of West Virginia twice this weekend, and made a few observations about the new setup. As a reminder, I now have the Tru-cool 40K transmission cooler sitting in front of the A/C condenser and a new Cold Case double-row radiator. All of this is cooling a drivetrain that makes an extra 50-60 HP & TQ over the stock 6.2L, thanks to a stage 2 truck cam upgrade.

Before any of those cooling system mods, my engine would run 200º-230º and my transmission would run 180º-235º when towing in 80º weather, depending on terrain.

After adding just the Tru-cool, my transmission ran much cooler, as expected, between 150º-180º when towing over the hills, which was a huge improvement, but my engine would run much warmer than before, between 220º-230º when towing on relatively flat ground in 80º weather, and I stayed out of the mountains as a result until I could sort it out.

Then, after adding the Cold Case radiator, my transmission temps are still nice and cool, and my engine temps now run 200º-210º when towing on flat ground, and it only gets above 220º when pulling up longer, steeper grades. In general, that's a significant improvement but still may not be enough.

On the way home yesterday, we climbed some long hills and because of traffic on I-81 had to keep our speed at 70 mph or above. It was about 78º outside and I noticed a couple of times my engine temp crept up to 240º but only for brief moments before cooling back down to 230º while still climbing the same grade. My guess is that's when the fans would kick into high gear and wrangle the temp back down. Also, the transmission never got above 180º.

Long story short, my conclusion is that while the Tru-cool is fabulous, its exceptional performance comes at the expense of radiator and engine cooling performance because of its positioning. I'll know more as the summer heat ramps up and we take some more trips, but my guess is that I'll have to take some additional steps to restore the balance of cooling system performance between the engine and transmission. I may experiment with a remote-mounted Derale fan-assisted transmission cooler in order to unblock the radiator. I'll update this thread as I experiment.

If any of you have any other ideas or things I should consider, I would welcome them - especially ideas for how/where to mount a Derale cooler, or even to re-position the Tru-Cool.

 

[kbuskill]

Just an update here. I towed our 6500 lb camper over the mountains of West Virginia twice this weekend, and made a few observations about the new setup. As a reminder, I now have the Tru-cool 40K transmission cooler sitting in front of the A/C condenser and a new Cold Case double-row radiator. All of this is cooling a drivetrain that makes an extra 50-60 HP & TQ over the stock 6.2L, thanks to a stage 2 truck cam upgrade.

Before any of those cooling system mods, my engine would run 200º-230º and my transmission would run 180º-235º when towing in 80º weather, depending on terrain.

After adding just the Tru-cool, my transmission ran much cooler, as expected, between 150º-180º when towing over the hills, which was a huge improvement, but my engine would run much warmer than before, between 220º-230º when towing on relatively flat ground in 80º weather, and I stayed out of the mountains as a result until I could sort it out.

Then, after adding the Cold Case radiator, my transmission temps are still nice and cool, and my engine temps now run 200º-210º when towing on flat ground, and it only gets above 220º when pulling up longer, steeper grades. In general, that's a significant improvement but still may not be enough.

On the way home yesterday, we climbed some long hills and because of traffic on I-81 had to keep our speed at 70 mph or above. It was about 78º outside and I noticed a couple of times my engine temp crept up to 240º but only for brief moments before cooling back down to 230º while still climbing the same grade. My guess is that's when the fans would kick into high gear and wrangle the temp back down. Also, the transmission never got above 180º.

Long story short, my conclusion is that while the Tru-cool is fabulous, its exceptional performance comes at the expense of radiator and engine cooling performance because of its positioning. I'll know more as the summer heat ramps up and we take some more trips, but my guess is that I'll have to take some additional steps to restore the balance of cooling system performance between the engine and transmission. I may experiment with a remote-mounted Derale fan-assisted transmission cooler in order to unblock the radiator. I'll update this thread as I experiment.

If any of you have any other ideas or things I should consider, I would welcome them - especially ideas for how/where to mount a Derale cooler, or even to re-position the Tru-Cool.

Since you have a GMC, maybe stick the trucool down behind the "lower grille" in your bumper.

 

[HD_LS]

Are you still running the transmission fluid through the radiator tank cooler, before sending it to the Tru-Cool 40K? I second the previous recommendation to route the transmission fluid to the Tru-Cool only, and keep it out of the radiator tank. This will restore some balance by not having your engine coolant directly heated by the transmission fluid. This will help whether you move the transmission cooler or not.

Are your fans programmed to come on at cooler than factory temperatures? I also like the idea of using the more powerful fan motors.


In case the thermostat max opening area is a coolant flow restriction: Remember that flow restrictor you put in the hose between the upper rad tank fitting and the coolant tank? You could put a valve in to bypass that restricion when you are towing. (since that flow bypasses the thermostat)

 

[Geotrash]

Since you have a GMC, maybe stick the trucool down behind the "lower grille" in your bumper.

That's a good idea. I will investigate that. It's backed by a solid plastic piece right now, but that could be drilled out.

 

[Geotrash]

Are you still running the transmission fluid through the radiator tank cooler, before sending it to the Tru-Cool 40K? I second the previous recommendation to route the transmission fluid to the Tru-Cool only, and keep it out of the radiator tank. This will restore some balance by not having your engine coolant directly heated by the transmission fluid. This will help whether you move the transmission cooler or not.

Are your fans programmed to come on at cooler than factory temperatures? I also like the idea of using the more powerful fan motors.


In case the thermostat max opening area is a coolant flow restriction: Remember that flow restrictor you put in the hose between the upper rad tank fitting and the coolant tank? You could put a valve in to bypass that restricion when you are towing. (since that flow bypasses the thermostat)

Routing the transmission cooler direct is a good idea, but my worry with that is for the winter when there is benefit to warming the fluid a bit from cold. But, I could also add a thermostatic control valve in the circuit, I suppose.

Fans are still programmed to come on at the factory temps. I bought the 700w fan motor for the drivers side, along with the correct fan blade, and will install both this weekend.

Thanks for offering some good ideas.

 

[HD_LS]

What motor and fan blade part numbers did you settle on? Where did you buy them from?

 

[Geotrash]

GM Genuine 20903474 Engine Cooling Fan Motor Kit https://www.amazon.com/dp/B00GU8W55...abc_GZ0VKH7WHJ2G0057MQAH?_encoding=UTF8&psc=1

GM Genuine 20897351 Engine Cooling Fan Blade Kit https://www.amazon.com/dp/B00GU8YIF...abc_2FEGAH6GBKJ740V6A7WG?_encoding=UTF8&psc=1


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[HD_LS]

Thanks!