Originally Posted by aeroflyer550

I am going to be pulling a trailer close to max weight, which is for my truck between 26k to 30K, does anyone know if I need to install an aux transmission cooler like the Tru-Cool 40K? My truck has a ZF6 manual tranny and it has a lines to a cooler which is part of the rad. I am wondering if I pull this trailer am I able to keep the temps in the tranny under control? Do I need to use the Thermostatic bypass valve to keep temps under control? Is the pump in the tranny capable of constant flow through the aux cooler. I know the thread is long.

Originally Posted by SWV10

My '07 F150 XLT has the 7 roll 22" long cooler and can't handle my towing needs. My tranny is running 265, trans oil changed twice now in 15,000 miles because of the high temp heat.
I am towing a 5000# travel trailer over a mountain range.
The 1st 14 miles I climb 900 ft in elevation,a few curves but mostly straight highway and starting at the 6400ft elevation-Overdrive off, F150 shifts between 3rd and 2nd but mostly stays in 3rd. Towing at the speed limit of 50,trans temp reads 185 w/additional aux cooler installed. Next 4 miles I Climb another 900 ft in elevation, lots of curves, steep climb, speeds not over 35, 2nd and downshifts into 1st 3 times. Halfway up this 4 mile section the Engine cooler clutch fan kicks in, stays on for a couple of minutes, trans temp at halfway on this 4 mile hillclimb point is 245, engine clutch fan cycles on and off for the next 2 miles. The Next 11 miles I stay in the 8200-8500 ft elevations, OD still Off, trans cools down to 210, speed is 50mph. The Next 5 miles is on a rough Forest Srevice Dirt Road, speed in the 10-15mph range, temp reaches 265 on the next steep curvey hillclimb of 800ft, which still keeps me in the mid 8500ft elevations, as I drop down into a meadow when turning onto the Forest Road. After I top out on the Forest Road, the Trans temp settles back down to 240. Raises again to 260 for the last mile.
Way too Hot.
I had my Ford Dealer install the Aux Tranny cooler(as the F150 is still under the Factory Warranty), it sits in the left corner(pass side) and above the stock trans cooler for better air-flow, the aux cooler is 11"Hx8"Wx1.5"Deep. I was assured that this Aux cooler would do the xtra cooling fine, Not So.
My Ford Dealer is great, they gave me a Full refund of the Install and Aux Trans cooler and now I am looking at the B&M Hi-Tek Supercooler # BMM-70298, out of the two models with the High-flow 12v fan, the 70298 will fit in the same space as the current Aux-cooler with no cleareance problems. Hopefully with the fan assist and thermal switch, I can keep these High Temps down into a more comfortable range.

Any other idea's or Aux cooler's I should look at other than this B&M?