I am about to install an oil cooler on a 5.2 318. I don't know which is the return line the one that connects to the bottom of the rad or the top? I think it is the top because the lower one seems to have some sort of valve on it. I am not sure, also is the hose 3/8th or 5/16 th's and could I use power steering hose instead of transmission hose?

Thanks for any information.

 

Hose is 3/8ths, Get rid of the check valve, bottom hose is the line TO the radiator. (hot line) parts store should have trans-specific hose for pennies per foot. (ok, maybe quarters....)

 

I checked at O'reileys, AZ, Advanced, and even Wal-Mart but no body seems to have more than 2feet of Transmission hose. All I can get ahold of is powersteering hose with is $2.60/ft.

So the bottom hose that connects to the bottom of the rad is the hotline with the infamous check valve, correct?

Should I put the cooler before or after the rad?

 

I would think power steering hose would work...... not cheap though, is it.....

Yep, bottom hose needs some attention. Lose the check valve.....

In your area, I would plumb the aux cooler in AFTER the radiator cooler.

 

don't use power steering hose. hold out for auto trans hose.
it'll run $3 per foot.
https://www.napaonline.com/Catalog/C...258671883&An=0

i second to plumb the oil to the radiator first, then the aux cooler.

 

YES! Radiator first!! lol i tried this little experiment. Think of it this way, Out of your trans its 200degree we will say. If you go through the cooler first then when you go to the radiator you may warm it back up because the radiator is running around 180 to 190. If you run to radiator first then you cool down from 200 to 190ish. Then it goes to the cooler where temps go from 190ish down to 150-170ish. All depends on load and driving style.