thorpedo91

i have a 1969 cutlass s. turbo350 trans and the high compression 350 motor. i just rebuilt the motor, my first rebuild, and i put it back in, hooked everything up, and everything is running perfect, except one thing. The two ports for the transmission lines in the radiator go directly to the water filled part of the radiator, and to my understanding, the transmission circulates trans oil through the radiator in order to cool the transmission, well the oil right now is mixing with the water, so i believe that is not how it is supposed to work. the radiator is brand new, the previous owner bought it and never installed it. so, is there a seperate small radiator for the transmission, or did i hook it up wrong? or should i just ignore it? thanks!!

joe_padavano

If the trans oil was really mixing with the coolant, you would have milky oil in the trans and red droplets in the coolant. You would also have a burned out trans in a few miles.

The trans cooler is a separate passageway that is inside the end tank of the radiator. If you look down through the radiator cap opening when the coolant is drained, you can see the trans oil heat exchanger inside the end tank of the radiator.

Here's the final test. If you fill the radiator and unscrew the lower trans line from the radiator, does antifreeze come out? If yes, you have a bad radiator. If not, you're fine.

thorpedo91

that helps a bit, but one more thing. if i take off the radiator cap, and look down, i can see the hole where the top trans line comes in. It is just a hole, not connected to any pipe or unit or whatever. if i turn the car on, trans oil comes out of that hole and drops into the coolant, so it is definently mixing. Is it possible that this is a radiator for a manual trans? do they actually make manual trans radiators different than automatic trans radiators?

Yellowstatue

Sounds like your rad does not have a trans cooler installed in it!!! A manual trans rad does not have any holes in it in that location... Do not run car any more because you have contamination happening in the trans oil

thorpedo91

ok. so now i gotta know my options. im thinking that the best, cheapest choice is to just buy a transmission oil cooler, instead of a whole new radiator. anything else i can do, or is that my only choice?

ent72olds

You could go the cooler route, but you'd also have to re-run the tranny lines to the front of the radiator...I would replace the radiator. Would make for a neater looking application IMO. If the rad you have is good, you could sell it and recoup some of the cost...

citcapp

If the radiator is in good shape (the core) take it to a shope they can replace the tranny cooler. Get an estimate first to make sure your not exceeding the cost of a replacement radiator

joe_padavano

If this radiator is good (and I assume you have the plugs for the unused trans cooler holes) then I would keep it and run an aux trans cooler. Rerouting lines is easy, and the larger cooler will be better for the trans.

mugzilla

I bypass my radiator and run straight to the largest cooler I could find but then I'm in sunny california ...

We ran this aropund the other day ...

https://classicoldsmobile.com/forums...html#post77774

Yellowstatue

What goes around comes around

thorpedo91

ill go to a shop and see what it would cost to put in a transmission cooler, and compare that to exterior coolers. i will let you know how it goes. I also live in California. so its definetley not cooled around here.