Extra Tranny cooler not sufficient - what next ?

truck2trail

Original poster
Member
Apr 5, 2012
39
truck2trail said:
I'm taking it to the dealer next week. Should be a quick and inexpensive fix.

I felt sure I was correct in my diagnosis of the problem, so I didn't uncouple any tubes to determine the flow direction.

What's more, the Chevrolet dealer agreed with me. They flipped the connections, installed new springs and only charged me $71. Money well spent as the connections were in a difficult to get to location.

I'm now experiencing about 10 to 15 degrees F lessor transmission fluid temperatures than before on my Scanguage II. Still not sure whether this will be sufficient once I connect the trailer, time will tell. If it's not I feel more inclined to replace the current 3/4" thick unit with a Tru-Cool that's thicker, rather than add another in series.

Thanks for all the suggestions and comments.
 

truck2trail

Original poster
Member
Apr 5, 2012
39
So I pulled the trailer for two hours with an opposing wind of about 20mph and an outside temperature of 70 F degrees, but I couldn't go more than 55mph without the transmission temperature going over 200 F degrees. The radiator temperature also rose to 212 F degrees, whereas it's usually in the 190 F degree range. So obviously, swapping the tube connections has helped, but it's not as good as I'd like it. Don't know whether to replace the 3/4" tru-cooler with a 1.5" or not. Definitely, with the radiator temperature rising, I don't want to cover up any more of the radiator surface. Think I might go with it on the way to AZ this November and possibly upgrade to a thicker unit when I'm down there, depending on how it's behaved.

My conclusion is that I wished I'd gone bigger in the first place. As others have said on this forum, go BIG !
 
Dec 4, 2011
520
truck2trail said:
So I pulled the trailer for two hours with an opposing wind of about 20mph and an outside temperature of 70 F degrees, but I couldn't go more than 55mph without the transmission temperature going over 200 F degrees. The radiator temperature also rose to 212 F degrees, whereas it's usually in the 190 F degree range. So obviously, swapping the tube connections has helped, but it's not as good as I'd like it. Don't know whether to replace the 3/4" tru-cooler with a 1.5" or not. Definitely, with the radiator temperature rising, I don't want to cover up any more of the radiator surface. Think I might go with it on the way to AZ this November and possibly upgrade to a thicker unit when I'm down there, depending on how it's behaved.

My conclusion is that I wished I'd gone bigger in the first place. As others have said on this forum, go BIG !

I also agree with your conclusion, bigger is better. Now that, that is said you may want to compare the GVWR of the two coolers you are considering to get an idea of how effective going to a larger cooler might be. For instance is the 3/4" is rated for 15000 lbs and the 1 1/2" is rated for 23000 one would conclude that the thicker one is 65% or so better. I would think that this comparison is not linear but would still be a good indication of how much more effective the larger capacity one might be. My 4589 Tru-Cool is rated for 24500 lbs and works like a charm.

Good luck
 

truck2trail

Original poster
Member
Apr 5, 2012
39
truck2trail said:
Think I might go with it on the way to AZ this November and possibly upgrade to a thicker unit when I'm down there, depending on how it's behaved.

Yeh, well November has come around, and now nearly at the end of our migration from Ontario to Arizona, the result is that the above "fix" has made some improvement, but not enough. In Oklahoma, with a head wind of 25mph, a travel trailer with a blunt front end weighing about 2800lbs, I had to slow down to about 52mph to keep the TFT under 200 degrees F.

The acid test, climbing the Organ mountain on the East side of Las Cruces, was almost as bad as last year. We made it to about 0.5 mile from the top, but then I pulled over with the TFT at 220 and the rad temp at 228 (both measured on my Scanguage II). Let both cool down for 20 minutes, then made it to the top.

So I've decided that I definitely need a bigger Trucool, but now I'm concerned about the rad temp, which I didn't measure last year. How hot is too hot for a rad ? When will it start to boil. ? The IF (?) (aperture) temperature was 138 degrees F !

I really think I need a more powerful vehicle for this 4 month trip, but not for the rest of the year. What a dilemma !
 

strat81

Member
Dec 29, 2011
399
truck2trail said:
I really think I need a more powerful vehicle for this 4 month trip, but not for the rest of the year. What a dilemma !

Trade up for a V8 'voy? The mileage penalty isn't that bad.

According to the DIC, I got 20.5mpg yesterday on a ~110 mile trip doing 60-65mph the whole time. My DIC tends to be accurate within +- .5mpg. It's a V8 AWD Rainier with 3.73 gears and synthetic gear lube front and back, winter tires at 35psi.

The current-gen Tahoes aren't too bad either, but they are bigger and harder to park.
 

gboos

Member
Jul 22, 2012
34
I may coming way too late to this thread. Sorry, just read it now. What I read, and I hope I'm right, you already installed a 2nd cooler tranny cooler with much higher cooling capacity. Have you installed the new "bigger" cooler after the smaller and already installed cooler ? If so, than you should think about to change both in the position. The bigger tranny cooler should be installed in front of the cooler with smaller cooling capacity. To take the smaller first makes no sense, because the cooled fluid coming out from the smaller cold be already lower than the optimum on effectiveness factor of the bigger cooler, which makes him useless.

Therefore you better install the bigger cooler first, being able to take much more heat from the fluid and then let it run through the smaller cooler. If a 2nd cooler still makes sense. May the resistance of a 2nd cooler could be am issue for the pump in the transmission on the long run. But not sure.

Greetings Mike
 

Indybp57

Member
Jan 9, 2012
27
gboos said:
I may coming way too late to this thread. Sorry, just read it now. What I read, and I hope I'm right, you already installed a 2nd cooler tranny cooler with much higher cooling capacity. Have you installed the new "bigger" cooler after the smaller and already installed cooler ? If so, than you should think about to change both in the position. The bigger tranny cooler should be installed in front of the cooler with smaller cooling capacity. To take the smaller first makes no sense, because the cooled fluid coming out from the smaller cold be already lower than the optimum on effectiveness factor of the bigger cooler, which makes him useless.

Therefore you better install the bigger cooler first, being able to take much more heat from the fluid and then let it run through the smaller cooler. If a 2nd cooler still makes sense. May the resistance of a 2nd cooler could be am issue for the pump in the transmission on the long run. But not sure.

Greetings Mike

The "smaller" factory cooler is built into the radiator. You have no choice but to install the auxiliary (bigger) cooler in front of it because there is no room behind it. As far as the fluid routing, the auxiliary cooler manufacturer (in my case Trucool) recommends that the fluid pass through the factory cooler first, then through the auxiliary cooler. I suppose you could do just the opposite - I doubt if there is really much difference. The tubing diameter and passageways in the auxiliary coolers are much larger than the factory transmission lines and offer very little resistance. There are millions of these on the road and if it was an issue then it would have come to the surface.
 

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