Transmission Cooler Bypass?

[Roadmarks]

Howdy, I have added an external trans cooler and filter to the nose of my '71 C10. The outfit that I got It from, Makco Distributing, strongly suggests a "cooler bypass" for very cold starts. I don't mind adding it if it is really needed, but the original "in the radiator" cooler doesn't seem to need it. Are these guys just trying to stick their hands deeper in my wallet, or do I need to look into this further? My flow pattern will be through the filter then original rad cooler then through the add-on cooler. Comments or thoughts?

Thanks

[CE20934]

IMO, the bypass (add-on cooler only) would be handy if you see temps below 40 or so.

There's no bypass for the radiator cooler because that one doubles as a trans fluid warmer during cold weather running.

[Longhorn Man]

i would route it through the original cooler (rad) last. No need for a bypass at all

[raycow]

Longhorn has it right. Radiator cooler last. This also has the advantage of putting LESS heat into your cooling system when you are running hard and hot.

Ray

[cdowns]

when i lived up north in newyork i never had a cooler bypass the tranny worked fine even in below zero temps

[C20-67_N_MO]

Originally Posted by raycow

Longhorn has it right. Radiator cooler last. This also has the advantage of putting LESS heat into your cooling system when you are running hard and hot.

Ray

Originally Posted by cdowns

when i lived up north in newyork i never had a cooler bypass the tranny worked fine even in below zero temps

Originally Posted by Roadmarks

Are these guys just trying to stick their hands deeper in my wallet, or do I need to look into this further? My flow pattern will be through the filter then original rad cooler then through the add-on cooler. Comments or thoughts?

Thanks

These guys have all given some very sound advise.

[VetteVet]

This is how one transmission website shows it . It looks like the fluid routes to the radiator and then to the air cooler. I don't think it makes much difference but the trans fluid will transfer heat faster to the radiator fluid than it will to the air around the cooler.

[mrein3]

I doubt the coldest start in North Carolina is any where near where I've run my truck. I have an external cooler and no bypass.

I do know a guy that has an "H" plumbed into his system. He completely bypasses the coolers (radiator and external) on really cold days.

Plumbing wise you want the external cooler before or after the tank in the radiator depending on where you live.

Up north here you run the hot tranny fluid to the external cooler then to the tank in the radiator. This keeps the fluid a touch warmer. You can get it too cold.

Guys in hot climates will want to run it to the radiator then to the external cooler for maximum cooling effect.

Back to the bypass question. If you go without one, just wait until the truck warms up a tad before you take off if you're worried about it.

[Roadmarks]

@VetteVet, Thanks! I have that diagram and instructions that came with the cooler, and that is the way I plumbed it. I was just curious about the by-pass. At this point, I'll save the $35 and wait and see.
@mrein3, You got that right! We have a LOT more days over 90 than under freezing! Thanks!
@everyone else, Thanks for the input!

[turp mcspray]

I just put a piece of cardboard in front of my trans cooler in the winter.