Transmission cooler for off road/crawling questions

[77 K20]

Yesterday I spent all day with the off road club heading up to different old fire lookout sites. Of course these are up on top of mountains and the trails we took often went straight up the side of the mountain. Outside temp was around 79 degrees.

I spent pretty much the whole day in 2 low or 4 low. Most of the time vehicle speed was 5-25 mph.

I have the stock mechanical fan with a HD clutch on it. I'm thinking this provides enough airflow for a plate style cooler at low vehicle speeds... But I've seen where they have electric fans on them for more $$$ but they often are rated at only something like 500-600 CFM. So that isn't much good- right?

If the outside temp gets much above 85 I just stay at home- so I'm not gonna be out wheeling in 100 degree days. I do go out a lot in winter thru deep snow. So driving at temps of -10 degrees to 30 degrees will happen. I've heard transmissions don't like to be too cold either. So maybe I don't need the biggest cooler out there?

I'm looking at two different B&M units. #70266 rated at 20,500 BTU (11"x8"x1.5") and #70274 rated at 29,200 BTU (11"x 11"x 1.5").

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Thoughts? Is bigger always better? Even in winter?

Both have 1/2 NPT fittings on it. Many many years ago I had transmission coolers on my previous rigs- and had leaky hoses or a hose blow off. I'm not a fan of the rubber hoses... but maybe hose and barb fittings are better now than they were in the 1990s? Anything to be concerned about here?

 

[77 K20]

As far as cold temperatures there is this thing:

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Tru-cool sells it. A cold weather bypass. The thermal bypass starts to open at 180° F, and is fully open at 205° F. Sounds nice in theory. I however know it is now just 4 more points to possibly leak and blow off. And what is the reliability of this thing? Will it fail and bypass all the time?

 

[Frankenchevy]

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I have a new derale stacked plate cooler that’s a pretty good size, Hughes deep pan and Hughes XTM torque converter. I used hand flared nicopp at rigid to hose transitions and fuel injection style hose clamps with no leaks, but only 500 miles on my truck as is. The cheap flaring tool leaves some shallow checking behind the flare on softer tubing—which I think helps the hose/clamp grip.

My trans temps stay really stable both on the freeway and on slow gravel roads. I can measure my cooler later for you.

 

[77 K20]

Wow- always amazed at how clean that truck is.

What is a "fuel injection style hose clamp"? I know I've never been impressed with the radiator clamps for smaller hoses.

 

[77 K20]

https://www.haydenauto.com/Featured Products-Patented By Pass Cooler/Content.aspx


Just found this- I think I like this one a lot. Has an internal bypass.

 

[Frankenchevy]

What is a "fuel injection style hose clamp"?

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https://www.summitracing.com/parts/...p1U8083gTrulVSXf1TaGTqQWcZvFS6SBoCphsQAvD_BwE

 

[Frankenchevy]

https://www.haydenauto.com/Featured Products-Patented By Pass Cooler/Content.aspx


Just found this- I think I like this one a lot. Has an internal bypass.

That’s one of the nice things about good stacked plate coolers, the oil has to reach a certain temp/viscosity to flow through the cooler or it’ll bypass. Nothing else in-line needed.

 

[75gmck25]

Long Mfg. used to be the OEM supplier for B&M stacked plate and many other stacked plate coolers, but I don't know if that has changed. You can go to their web site and see the variety of coolers that are offered.

The low pressure drop (LPD) series works very well, and most have a low temperature bypass that allows oil to bypass the cooler until it gets hot. Make sure you have it mounted with strong metal brackets, with enough space that it does not vibrate against the radiator when you go off road.

I've always used the standard clamped hoses and connectors, but hard line and threaded fittings should be better at holding up. However, for OEM coolers they still put a short section of rubber hose in each hard line to allow some flex between the truck body and the cooler.

Bruce

 

[Matt69olds]

Since your running a 400, over cooling inst much of a issue. Overdrive transmissions with a lockup converter restrict cooler glow with the converter locked, that prevents to trans fluid from getting too cold when your driving in-20 degree temps on the highway. If your worried about the trans getting too cold, as long as you keep the radiator trans cooler you should be fine. Run the trans fluid thru the auxiliary cooler first, then into the radiator cooler. In the summer, the auxiliary cooler will take some of the heat out before it gets to the radiator. And in the winter, the radiator will warm the trans fluid after the auxiliary cooler. That’s my theory, without a actual trans temp gauge who knows if it will actually work out like that?