I'm adding a derale atomic cool fan/plate/fin tranny cooler. Should i keep the factory external cooler or bypass it?

 

Keep it. install a thermal bypass valve as well. (prevents over-cooling the fluid. too cold can be just as bad as too hot.)

 

Thanks. The derale unit comes with a temp sensor that kicks on the fan as needed. Is the bass valve still needed?

 

See what you temps look like over a few seasons. If you find it not even getting to 150 or so when it is cooler, install the valve. Otherwise, skip it.

 

Got it.. Thanks!

 

So I finally installed my Transmission Temperature gauge. Tranny is barely getting over 100 degrees when outside temperature is 60 degrees or less. I've found a derale bypoass valve that opens at 180 and a TruCool unit that opens at 165. I'm thinking the 180 would be optimum.

Fluid leaves the transmission, goes through an external filter then to the factory cooler then to the aftermarket cooler and back to the transmission. I'm measuring the temperature after the fluid leaves the transmission right before it enters the external filter. The factory cooler has a 100 degree bypass valve. I'm thinking of installing the 180 between the factory cooler and the aftermarket cooler. This should result in the factory cooler doing the bulk of the work until temps rise enough (either through environmental factors or workload) to warrant the second cooler kicking in. (second cooler has a thermostat controlled fan that kicks on at 180 also)

Thoughts?

 

Run the fluid thru the aftermarket cooler then thru the radiator mounted cooler.
The radiator cooler helps maintain proper operating temp at all times.
That way you shouldn't need a bypass valve.

Dave