Ok, Here we go...
1990 F-250 460, auto, 2 wheel drive

(I did the second external trans after the first pump seal blow)

Two external trans coolers, not connected to the rad, a gauge on the out pressure side to see what temp the trans oil is when leaving to cool off.

Ok towing down the road without over drive the temp....130 up hills down hills, flat land... at 58 miles and hour and pulling a 26ft alumilite 5th wheel.....

Put the truck in over drive the temp climbs to 160 to 180 and if you're taking a exit to stop the temp climbs to 210, 220 or higher causing the front seal to leak.

If you start towing and stay on the hwy....no problem.... if you take out of overdrive about 10 minutes before the exit, you can hold the temp down.... not by much

You can not tow around town, temp climbs.
Water temp is great, running a oil cooler so oil temp is great.
Trans temp jumps up and down real fast depending on the driving.

On idling the trans temp runs 110 out of trans on the way to the cooler.....

Any Ideas? could it be the trans pump blades got soft from a overheating before I put two trans coolers on and trans temp gauge?

Thanks for reading, I tried to put all the information in.

Wolf

 

How many 90 degree fittings did you use? I wonder if your lines/fittings/coolers have reduced your flow too much? Just a guess...

 

I made a inline T for the gauge so the trans oil flows inline, the main line goes out past the sensor then up to the top cooler one bend up the front out the bottom trans, a steel line loop, into the 2 cooler with a side entrance to keep the lines flowing then out with a loop back to the trans, I kept the soft bends to almost less then factory...

Thanks for the email idea, it was a concern with routing the trans cooler so I bought two types of mounts... bottom and side.

Thanks.
Wolf

 

Okay, that helps eliminate a common cause of flow restriction. 90 degree fittings are known bottle necks when it comes to flow. Next question...are the coolers in series or parallel? Sounds like series from your description. With all the twists and turns a typical tube and fin cooler has I question the flow restriction you now have. Maybe a bigger single cooler or changing the flow to parallel might be the next step.

You might also start considering your clutches are fried from previous overheating. You may be caught in a viscous cycle. The factory solenoid packs are known to stick causing low pressure, which now allows more slippage, which in turn creates more heat....

 

Sounds like not enough air passing through the coolers. May have to put some electric fans on them. I doubt the tranny oil pump is failing, they work or don't(been down that way before....)

Is there any shuddering on OD? Could be a bad torque converter too.