Many people complain about the Duramax fan clutch is way too freaking loud. I agree!!! My ears deserve a break...especially during summer & when pulling.
I am pondering buying the biggest tranny cooler I can get & then drain & replace the fluid with Transynd.
Hopefully this would cool the tranny enough when under moderate to heavy loads ( Pulling 8000 lb trailer during summer w/ AC on).

There is alot of anectdotal evidence from others on this forum that doing so may keep the tranny temps below 180-190.
I notice that my Fan Clutch only engages when the tranny gauge gets at or alittle above 200.

Does anybody have any experience doing so & whether this actually keeps the temps low enough to not experience the Fan Clutch "Hurricane"?

I have installed the Mike L. cooler, deep pan and torque drive fluid in my 07. I pull a 14K 5th wheel and even in Az my tranny temps run about 165* and then goes to about 190* pulling long hills. When pulling these hills for several miles my fan does come on, shuts down, gets warm again and cools back down. I don't think I have ever heard my fan come on when pulling 14K # on level or 3/4% grade so a cooler tranny may help.

I've done exactly the same thing as Dennis10 — except with Mobil Delvac ATF (an Allison TES 295 fluid). Chevy and Allison both suggested these mods. I pull a 13K 5er. So far, the trans temp is staying down, but I am waiting for truly hot weather for the real test. Engine temp has never been a problem. Trans temp would rise on long, steep pulls where the slow speed will not let the converter lock up. BTW, Chevy and Allison know of this problem.

Does anybody out there know anything about the following website...
transmissioncooler.us

They advertise various sizes of coolers desiged for Allison transmissions.

I wopuld like to keepo my options open if & when I select a bigger cooler.

Allison has a variety of coolers for its transmissions in different applications. But they won't fit your truck without significant modification. The Mike L. coolers bolt right in and they work.

I've done exactly the same thing as Dennis10 — except with Mobil Delvac ATF (an Allison TES 295 fluid). Chevy and Allison both suggested these mods. I pull a 13K 5er. So far, the trans temp is staying down, but I am waiting for truly hot weather for the real test. Engine temp has never been a problem. Trans temp would rise on long, steep pulls where the slow speed will not let the converter lock up. BTW, Chevy and Allison know of this problem.


Not so much a converter lockup problem, as there is a cooling loop in the radiator for the tranny. As the radiator (not engine) gets warm, so does the tranny. The engine has a thermostat that more or less mixes hot engine coolant with cool radiator coolant to maintain temps. The higher the rad temp, the more rad coolant / less recycled hot engine coolant. If the rad temps climb to the point that mixed engine / rad coolant is above ~200-210 then the temp gauge moves.. If it moves enough you have overheating issues.

I found the BEST and largest cooler for the truck at www.coolmyduramax.com. You want the Mike L cooler. 30 degree drop in temps. Add Amsoil fluid and it drops 40 degrees with the cooler. I bought two coolers from them and ran both in series. 2 coolers together.

Out of curiosity, what does a Mike L cooler cost?

Thanks

I found the BEST and largest cooler for the truck at www.coolmyduramax.com (http://www.coolmyduramax.com). You want the Mike L cooler. 30 degree drop in temps. Add Amsoil fluid and it drops 40 degrees with the cooler. I bought two coolers from them and ran both in series. 2 coolers together.


can you post a couple pics of the 2 of them installed?

Out of curiosity, what does a Mike L cooler cost?

Thanks

On the website, www.coolmyduramax.com they are $450 each. I bought two myself and they nudged it down a little on a package.

Definitely worth it.

When you want to completely rid the factory fluid, I connected everything up to the T-Tech fluid exchanger, had a 5 gallon bucket of Amsoil fluid flowing in and then the old stuff flowing out. Perfect fluid exchange. No old stuff left behind.

can you post a couple pics of the 2 of them installed?

I am way behind on taking pics and whatnot.. I will get some up asap for you . I had a bunch of pics - nearly 300 of the truck build and mods but the camera I had it all on had the memory card screwed up. (Dont buy those cheap taiwan made MY FLASH 2gb sd cards from ebay for $4!!!) So basically I have been taking pics here and there with the trusty iPhone...

Enahs,
How did this set up work in the truly hot weather you mentioned last July?
I got a long trip nied up in July & may want to try somethind tried & true.
Mike L may get some business from me.