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

[RooTBeeRthe1st]

Mutilated the junk stock end tank.
ID for the overflow is 3/8"
But on the inside of the tank, it's only 1/8" for the restrictor.
So now I know what to aim for on the Cold Case fix.

 

[Douglas Friedberg]

Read some of your postings. Interesting info.
I tow a 5000 lb load with my 2006 Yukon xl 5.3. Haven’t had the problems with my two 1500 mile trips. Other then keeping it out of overdrive going through the KY mountain area. I wonder what the diff are between the two trucks. But was in sept. So cooler air maybe playing a big part and your wind resistance as well. From talking with a lot of other people that tow I found one very interesting idea. The transmission makes a lot of unwanted heat and many have tried many ideas with trans coolers but the one that does work the best is a cooler for the trans under the truck. It’s get rid of the heat faster without transferring it the engines system. Food for though.

 

[Douglas Friedberg]

Read some of your postings. Interesting info.
I tow a 5000 lb load with my 2006 Yukon xl 5.3. Haven’t had the problems with my two 1500 mile trips. Other then keeping it out of overdrive going through the KY mountain area. I wonder what the diff are between the two trucks. But was in sept. So cooler air maybe playing a big part and your wind resistance as well. From talking with a lot of other people that tow I found one very interesting idea. The transmission makes a lot of unwanted heat and many have tried many ideas with trans coolers but the one that does work the best is a cooler for the trans under the truck. It’s get rid of the heat faster without transferring it the engines system. Food for though.

Many transmissions burn up towing and that idea eliminates the problems.

 

[RooTBeeRthe1st]

Yeah, I have mine in front of the radiator only because that's where the factory auxiliary cooler already was, but when I put the supercharger on, the intercooler for that will be taking up the real estate I'm using for the true cool that I put there. So I'll end up finding a spot underneath somewhere, likely putting a fan or two on it. But that's a good little ways down the road still before I need to worry about that.

 

[Tallpaulboise2]

It's audible, but not from inside the truck so it's not as loud as the main cooling fans by any means. I'll pretty much guarantee your Tru-cool will be plenty to keep your trans temps below 230, even towing up a 7% grade for miles, as long as it has good airflow through that lower bumper fascia. It's so much more effective than the factory cooler.

As for pics, if I'm using a computer, I take a screenshot of the image and paste it into my post in the browser. If I''m using my mobile phone, I use the insert picture feature on the forum and select them from my camera roll.

Please do keep us posted on what you learn!

Picked up my trailer from servicing and headed for the freeway. 97 degrees outside. After 12 miles of driving over moderate hills the trans temp hit 185. Then I looked at my engine temp and it was 230.
I turned around to head home and had to get off the freeway because of an accident. I had 25 minutes of stop and go traffic and the temp hit 201 once. The trans temp problem is looking good but now I have to diagnose the high coolant Temps. I know the drivers side fan has a high speed but does the passenger side fan step up also? I have never heard it. I think I need to go back and check the threads for info on my fans.

 

[Doubeleive]

Picked up my trailer from servicing and headed for the freeway. 97 degrees outside. After 12 miles of driving over moderate hills the trans temp hit 185. Then I looked at my engine temp and it was 230.
I turned around to head home and had to get off the freeway because of an accident. I had 25 minutes of stop and go traffic and the temp hit 201 once. The trans temp problem is looking good but now I have to diagnose the high coolant Temps. I know the drivers side fan has a high speed but does the passenger side fan step up also? I have never heard it. I think I need to go back and check the threads for info on my fans.

fans should both turn at the same speed there is no left/right control, I believe the 7/9 blade design is only for noise control, then they went to a 5/5 blade

 

[mikeyss]

The 7/9 is rimmed, the 5/5 have no rim - both shrouds look different in the front too. I have both styles of these fans, all 700W motors. Honestly I don't know which ones flow best, but I find:
7/9 rimmed is in my 06 Sierra Denali with LQ9 all stock and original radiator with 186k on it, temps sneak up just past the middle line in 95+ degree weather, these fans are much quieter, even on hi.

5/5 is in my 09 Tahoe with L9H and mishimoto radiator and I haven't seen anything over 200 degrees, not even in 100 degree weather. These fans are very noisy, but that's a small price to pay to keep things cool. With the windows up, I can't hear them.

 

[RooTBeeRthe1st]

I have the 5/5
How would I know if either of them is 700 watt motor?

 

[Tallpaulboise2]

View attachment 344838
View attachment 344839

The 7/9 is rimmed, the 5/5 have no rim - both shrouds look different in the front too. I have both styles of these fans, all 700W motors. Honestly I don't know which ones flow best, but I find:
7/9 rimmed is in my 06 Sierra Denali with LQ9 all stock and original radiator with 186k on it, temps sneak up just past the middle line in 95+ degree weather, these fans are much quieter, even on hi.

5/5 is in my 09 Tahoe with L9H and mishimoto radiator and I haven't seen anything over 200 degrees, not even in 100 degree weather. These fans are very noisy, but that's a small price to pay to keep things cool. With the windows up, I can't hear them.

I have the 5/5 setup. Im surprised that I don’t have enough air moving thru that radiator at speed to keep things cool. I know the driver’s side fan has a high speed but have never heard the passenger side fan hit a higher speed. Should it? I have read somewhere about getting an H P tuner (?)to change settings on one or both of the fans. Is this someone at a performance shop can do? Looking for answers.

 

[Doubeleive]

I have the 5/5 setup. Im surprised that I don’t have enough air moving thru that radiator at speed to keep things cool. I know the driver’s side fan has a high speed but have never heard the passenger side fan hit a higher speed. Should it? I have read somewhere about getting an H P tuner (?)to change settings on one or both of the fans. Is this someone at a performance shop can do? Looking for answers.

I could be wrong but there is 2-fans, 2-speeds hi/lo, 1-relay. no way for them to spin at different speeds unless one motor is defective.