Hi guys, just picked up an '05 FX$ SCREW 5.4 with factory tow package to replace the '99 F250LD. Truck is 100% stock as far as I can see. While poking around under the truck, I saw what I believe is an aluminum "block" in the tranny cooler lines about 2/3 of the way back from the cooler to the trans. maybe 3" square by 1.5" or so thick, both supply and return lines to the cooler run thru it via screw-in fittings.

1) What is this block? Metering? Valve which opens/closes depending on temp? Sensor?

2) Anyone tap into the lines here for a temp sender? Seems like with the right fittings I could plumb in an aftermarker sensor without cutting the lines?

Any help appreciated, thx!!

 

That is a bypass in case the cooler plugs so you still get flow. It also works when the fluid gets too cold to give flow while the transmission is warming up. I have seen them on certain vehicles through the years. Always seemed to be canada cars(and trucks) that had it.
Alan

 

It's a thermostatic valve that doesn't allow trans cooler flow until the fluid gets to about 185 degrees F.