Do I even need to use radiator to cool tranny fluid if...

[Kfort]

I am currently swapping out my 3 speed saginaw for a 700R4. My stock radiator does not have fittings to attach tranny cooler lines. I bought a Derale 13.7"x13.0"x2.0" stacked plate tranny cooler to mount in front of radiator thinking this alone might suffice. I haul a 3,000lb cabover camper from time to time and small single axle trailers on occasion as well. I do live in AZ were road temps can get hot.
Should I get the correct radiator for an automatic tranny and run in conjunction with the cooler? Or, might just the cooler work? Summit has an OEM type radiator with good reviews but a few people noted the aluminum was a bit lighter gauge.
Vehicle description: C20, 350ci slightly pumped up, A/C.
Thanks in advance

[grndcont]

Good question. In AZ you may benefit from the radiators heat exchange given your high air temps. I guess you could try just the independent tranny cooler while monitoring the fluid temps.

[sick472]

This topic can go nuts because there are so many way to build a truck and so many climates. So, my two cents say that these old trucks did not have tranny coolers to begin and the radiator did them just fine all alone. Now, if you are building the truck up beyond stock and hauling heavy, adding a cooler in line with the radiator is a good thing. You might be able to get by on just a cooler in your area, but you will have to have a temp gauge for you tranny to keep an eye on it, just to make sure. Another thought is that the radiator helps bring the tranny fluid up to temp quicker in the cold seasons as transmissions can be temperature sensitive and too low of a running temp is not good either. 180 F has always been a good place to be for me with 200 at the high end (under load/work scenarios).

[Orange Crate]

Same question came up last week when I was helping someone finish an LS/700R4 install. We put a temp sender in the trans pan to get an idea how it will run with just a small external cooler. That truck will be operating in Florida.

[weq92f]

For about the same money as swapping out your rad, you could probably install a fan on your cooler and control it with a relay driven by a thermal sending unit
installed right there in the cooler.

I like the idea of using a gauge just for peace of mind.

-klb

[OKGMC4]

My Dodge Ram came from the factory with an external cooler only. It's huge, though, like AC condenser huge. It has the tow package and does just fine. On the other hand my 56 GMC with a 4L60E and 3200 stall converter has the radiator cooler, a small Hayden plate cooler, AND a Derale remote mount cooler with a fan and will still instantly peg 180 degrees with one zero to 60mph romp. Just depends on the truck. Get a trans gauge and keep an eye on it.

[trukman1]

Originally Posted by sick472

This topic can go nuts because there are so many way to build a truck and so many climates. So, my two cents say that these old trucks did not have tranny coolers to begin and the radiator did them just fine all alone. Now, if you are building the truck up beyond stock and hauling heavy, adding a cooler in line with the radiator is a good thing. You might be able to get by on just a cooler in your area, but you will have to have a temp gauge for you tranny to keep an eye on it, just to make sure. Another thought is that the radiator helps bring the tranny fluid up to temp quicker in the cold seasons as transmissions can be temperature sensitive and too low of a running temp is not good either. 180 F has always been a good place to be for me with 200 at the high end (under load/work scenarios).

These trucks also didn't come with 700r4 trannies either...just sayin'!

[mygmctruck1]

So why not just put a cooling rad in ? They really aren’t that expensive .

[jocko]

it's a good question Kfort. I honestly don't know if the cooling capacity of the add-on Derale cooler matches the cooling capacity of a more factory auto trans cooler set up. Personally, if it's not too much trouble, I would install a radiator plumbed for auto trans cooling and a trans temp gauge - and hold the Derale cooler in reserve and see if you need it. If not, you're good. If you have the opportunity to return the Derale unit now (if you do opt for an aut trans radiator) but are running out of time to return it before you get the radiator installed etc, then might be best to just return it now - you can always buy another if you aren't satisfied with your resultant trans temp with the auto trans radiator.

Or, you could do the same with what you have now (and add a temp gauge) and see if you need the auto trans radiator. Either way would work. BUT, for some reason, my understanding of aftermarket trans coolers was that they were more or less designed to augment existing auto trans cooling in HD applications, not necessarily replace the presence of an auto trans radiator. But I don't know that for certain to be honest.

Bottom line - trans temp gauge is a worthwhile investment considering the fact that you're hauling a camper in Arizona...

[Smitty]

I did mine 20 some yrs ago. Bought the trans from Bow Tie overdrive. It came with the temp sending unit in the pan. Also can be used to drain the trans. At the time they recommended installing a hefty aux. trans cooler along with the regular automatic radiator. Didn’t have the selection then that’s around now so I used a Hayden whose application was for a motor home. In all that time it never overheated. Not even the day the trans grenaded about six weeks ago. Had the trans rebuilt and works as good as new! Old saying. “Rather be safe than Sorry”. My 2 cents.

[KQQL IT]

Sb 400 th400 with a 4k converter.
Cooler with a fan. Nothing thru the radiator.
Doesnt cook the atf must be ok?

Anything with a working lockup would run cooler than mine.

[MARKDTN]

Originally Posted by mygmctruck1

So why not just put a cooling rad in ? They really aren’t that expensive .

I would not want an automatic that towed without an internal radiator cooler. They help maintain temperature, not just cool.

[72c20customcamper]

I would run a trans cooler in the radiator too. As said it helps to heat the oil in cold weather

Originally Posted by OKGMC4

My Dodge Ram came from the factory with an external cooler only. It's huge, though, like AC condenser huge. It has the tow package and does just fine. On the other hand my 56 GMC with a 4L60E and 3200 stall converter has the radiator cooler, a small Hayden plate cooler, AND a Derale remote mount cooler with a fan and will still instantly peg 180 degrees with one zero to 60mph romp. Just depends on the truck. Get a trans gauge and keep an eye on it.

Yes there is no cooler in the radiator but if yours is like mine there is a plate cooler/heater on the side of the block . Trans fluid goes to the cooler in front of the radiator then goes to the plate cooler the exits back to transmission. This plate cooler has engine coolant running to it . Its main function is to warm the trans fluid in winter. I am replacing all the lines as they are rotted

[67ChevyRedneck]

Ugh, I don't miss that about NY (left 20 years ago). Brake and fuel lines and mufflers... every 8-10 years.

Good point about the radiator also warming the fluid when it's cold.

I don't really know the answer, but I have both on my 700R and it's survived 15 years, 70K miles, and way too many burnouts. I have a factory brass 4 row with an external cooler as well.

[72c20customcamper]

Originally Posted by 67ChevyRedneck

Ugh, I don't miss that about NY (left 20 years ago). Brake and fuel lines and mufflers... every 8-10 years.

Good point about the radiator also warming the fluid when it's cold.

I don't really know the answer, but I have both on my 700R and it's survived 15 years, 70K miles, and way too many burnouts. I have a factory brass 4 row with an external cooler as well.

Can't complain. Winter plow truck 12 years old it's made 15 times what I paid for it. And at least 80 cords of wood so far