Aux trans cooler upgrade, thickness..is bigger better?

Mossyoakglock · July 15, 2015

I am going to upgrade my stock aux cooler here soon. Yesterday in 96* heat my trans temp reached 190. I don't tow or haul many heavy loads often but I just want the temps a little cooler.

I know most everybody is going to say to go with the TruCool 40K but I'm not looking to spend that much. I've narrowed it down to the B&M, Hayden or DeRale. All are 11" long and range from 7 1/2 to 9 1/2" tall. I'm going with that size for ease of fit so I don't have to cut/notch any supports. My question is on width. The B&M (# 70264, 14400 BTU) is 1.5" thick, the DeRale 9 row & 13 row, 9000 series (17500 GVW and 22000 GVW respectively) is 1.25" thick and the Hayden 678 is 3/4" thick.

Is it better to get a thicker or thinner cooler? I thought I read that the 3/4" is better because it dissipates heat quicker than the thicker models.

sahls01gmc · July 15, 2015

190 is nothing. Your warning light won't even go off til 250. The fluid should at a somewhat high temp anyways. I say leave it!

Mossyoakglock · July 15, 2015

That was cruising down the interstate (15 miles) and then about 5-10 min to the house. It was 193* to be exact.

That seems high for just driving with no load.

sahls01gmc · July 15, 2015

Hmm, I'll check mine next time I drive it. I hear what you're saying though, "what's it going to get up to if/when I haul something with heat, hills, etc......?"

Chris · July 15, 2015

That is why you go big with the cooler

wrc7732 · August 4, 2015

After seeing this thread I decided to look at mine today. It hit 190 in maybe 95 degree GA heat, cruising down the road at about 40mph after only driving for maybe 10 minutes.

Never really paid much attention to it except when towing. Can't imagine 190 is considered high though.

Definitely considering an auxiliary cooler myself.

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Chris · August 4, 2015

I went thicker but it is not necessary. My cooler is overkill, but i live in a warm area and was towing on a regular basis. My prior cooler was a B&M that was 11x8x0.75. But once again i live in an area that hits 100 almost daily in summer, in winter i overcool the fluid and it doesnt even hit 110°.

wrc7732 · August 4, 2015

So, did some more observing this morning. Was running right around 190, in 72 degree ambient temps. Seems to get up to that point and then hang out, almost as though it's thermostatically controlled like coolant. Not sure if that's the case of not, but once it hit 190 it dropped back to 188 or so, and then came back up.

Seems to want to be at 190. Probably the optimum operating temperature for the fluid.

Update: 99 degrees this afternoon. Trans temps running between 187 and 192.

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takoda67 · August 10, 2015

The transmission lines run to the radiator so it will run at the same temp as your radiator. This is typical of all GM cars and trucks except HD and larger trucks that are built for pulling.

I would suggest the Derale with a fan that is thermostatically controlled. I have seen the kits on their website and on Amazon.