GM transmission cooling upgrades

[phbiggs]

Silvertwinkie that is a fantastic write up, best I have seen on the web yet!! I have been looking at using the same B&M 70266 cooler but could not find any write ups on the web. Could you provide more detail on how you avoided modifying the stock cooler lines?

The best info I have been able to gather up is that I would have to use a reducing adapter from the stock lines to the B&M.

Thanks
Phil

[Silvertwinkie]

Just going through some of my old posts and came across this one. Thought it'd be a good follow-up topic now that we're about to get into the heart of the travel season.

It's now going on about 5 years and about 17,000 miles on these mods and I can say without question it was for sure the right thing to do. No issues whatsoever. In fact, even in -15F this past winter (one of our coldest on record), the trans performed flawlessly. The Amsoil ATF I have in place has a pour point that goes down to -60F (even colder than my radiator fluid will currently tolerate).

In all the truck's transmission temps are consistently below that of the stock setup and I have been completely pleased with the overall short and long term results in all seasons and types of use. Of course, your results can and will vary.

To answer phbiggs' question, though a bit late, yes, I simply took the reducers off the stock cooler and re-installed them (carefully) into the B&M cooler (after putting some thread sealer on them) and connected the factory lines to the new cooler.

[Silvertwinkie]

Just wanted to give a quick update for this thread. It's now been almost 9 years with this setup and it continues to meet or exceed the desired outcome. In both extreme cold (-20 F), high outdoor ambient temps (97 F) and just about everything in between, the cooler and pan continue to flawlessly outperform the stock setup while towing or not. There have been ZERO issues in these 9 years with nearly 40k trouble free miles. This will be my last update on this thread as I think nearly 9 years of use does validate the mods (at least for this vehicle). Your results can and will vary.

PM me if you have questions or want to discuss further.

Happy, safe and cool travels!

[Airstreamer67]

Silvertwinkie, you deserve an award for an excellent initial write-up and perhaps the greatest follow-up(s) in the annals of the Internet!

I too added an external cooler on the tranny of my '96 F250 diesel a few years ago. That tranny used to heat up to 225F or maybe a bit more while towing in hot weather. The factory's external cooler was ridiculously tiny similar to yours, so I replaced it with a big 9 x 23-inch Tru-Cool unit along with a B&M external spin-on filter kit. Now, my temps have been reduced by 25 to 30F or more, which I'm sure will extend the life of my tranny. It's still pulling flawlessly.

[Silvertwinkie]

Ok, I know I said last post on this would be my last, but I just took a 3000+ mile trip to Badlands through Yellowstone and back. I was on grades anywhere between 6 and 8% during this trip.



On the interstate, in 90-95 degree ambient temps, I was around 170 with the Airstream in tow. Further west I got, I may have hit 180, but 170ish was my norm. I took I-90 all the way until 191 south to West Yellowstone.



I got overly confident and brave and decided to go from West Yellowstone and exited from East Yellowstone through Cody and through the Big Horn mountains (with fully loaded Airstream in tow)...taking the (ha ha) less stressful highway 16 (can't imagine trying this on highway 14 or 14a if 16 was the nicer of the three in terms of towing).



On grade (between 6% and 8%), it was slow to reach 200 degrees, but it eventually did during the longer runs at grade (2-5 miles). As some know, even on 16, there are some significant grades to cross and they are very long. I think I peaked at 205, and it would quickly drop back down to about 180...at or near 85 degree ambient temps.


Going through the Badlands yielded similar results.


So on average grade and interstates, what I've seen consistently is normal and lower than the stock setup was able to provide. However, at significant grade, especially in longer duration (with fully loaded Airstream in tow) I did hit and slightly break the 200 degree mark. Honestly, I don't feel pulling a combined weight of about 15k lbs could have done significantly better with a gasser setup even with my 4.10s at these grades and duration....diesel maybe (in terms of trans heat). I do not feel putting the next size larger cooler would have been a dramatic difference, but I am fairly certain that the setup was able to do far better than the stock setup based on my findings initially with the stock setup.



So I have now run a good spectrum of towing with this mod and am still very pleased with the results. I would have liked to have been sub 200, but not sure that was entirely realistic given the load and the grades I crossed.



For those of you that are not flatlanders like I, my hat is off to you. This was my first real long and at grade hauling and it was an experience. I half jokingly said to a friend, anyone that lives out that way and does this kind of stuff regularly, I can't imagine a tranny living more than 75k.


Happy towing!

[ITSNO60]

One of the first things I did to my Powerstroke was change the factory tranny cooler to the big 6.0 cooler. I ran it for about a year but noticed in the winter (even in Arizona) I had trouble getting the temps over 140. I read that about 170-180 is needed to keep moisture burned off so I installed a Derale 180 degree thermostat in the line that would cause the fluid to bypass the cooler when it was under 180 (It will still pass thru the radiator cooler). Now my tranny runs 180-190 summer and winter with momentary periods of 195-205 when climbing steep grades at 75-80 MPH (8,600 lb tow vehicle only no trailer). When towing a 7K trailer last summer she never went over 195 but I never exceeded 62 MPH either. So in my case the higher speed got it hotter than the extra weight, although 8.6K for the truck alone is a lot of weight in itself.

I would still like to see 170-180 average but there is not a thermostat made for the application that I am aware of.

I put the TruCool on my Chevy 3500 gasser work van (12K) with no thermostat and it only hits 180 in the summer, probably stays too cold in winter but it's my work van and I don't really care enough about it to put a T-stat on it. I do change the fluid every so often. Before the TruCool & gauge I don't know how hot it got but when I went to change the fluid at 24K it was BLACK. Flushed it all out and now at 107K with no issues.