Hi,
what pressures are in oil lines going from tranny to radiator? I'm going to fit additional oil cooler for tranny..
And while we are here what is optimal operating temperature for 700r4?
thanks

 

Most of the time, there's very little pressure; 10-15 psi. But it spikes up much higher sometimes as well, over 50 psi it would seem in some cases.

That's why people why try to cheeeeeeeeeep out and use fuel line, have leaks.

Optimal temp is something around 165 - 180°F. If lower than that, the fluid can't do its job; higher, and it starts to become acidic and otherwise destructive. Most of the better coolers you can buy that are intended for that purpose have a thermostatic valve of some sort, set to about 160ish, such that if the temp is below that, it sends the fluid back to the trans without going through the cooler (which is why if a trans blows up, you need to change the cooler, because blowing it out with air or even solvent doesn't do anything, because the valve is in "bypass" if it's cool). You can also use a "generic" cooler like a Setrab and an external valve. Use power steering return hose at a minimum, or preferably stainless steel braided hose with AN fittings.

 

The cooling system hoses carry more pressure and use rubber hose and clamps.

If you got 50psi in your cooler line, your tranny is F'ed up.