99 Suburban radiator

I am trying to replace my radiator due to a transmission fluid leak in the transmission cooler. I had no idea there were so many options on radiators. I bought one at Autozone but the transmission lines did not fit. Also, is it o.k. to get a radiator that has the oil cooler if I do not have an oil cooler setup? That was all they had.

I have noticed that the heavy duty radiators come with the TOC adapters. What do you recommend? Can I get an aftermarket rad that the transmission lines will fit without having to get adapters?

Thanks for any suggestions.

i needed a new rad last year..i went to a radiator "warehouse" and ended up with TOC adapters too..having an unused oil cooler won't hurt..cap it off..

The factory trans cooler (a pipe running through the hot water radiator) didn't keep my first 700R4 from frying at only 85,000 miles. Little more than worthless. If I hadn't had it maybe the trans would have blown while it was still under warranty!

Get an aftermarket mini-radiator style cooler such as Hayden makes, at least as big as a license plate, and attach it to the front of your new radiator where it gets plenty of airflow. Voila, at least doubled trans life for less than $100.

The factory trans cooler (a pipe running through the hot water radiator) didn't keep my first 700R4 from frying at only 85,000 miles. Little more than worthless. If I hadn't had it maybe the trans would have blown while it was still under warranty!

Get an aftermarket mini-radiator style cooler such as Hayden makes, at least as big as a license plate, and attach it to the front of your new radiator where it gets plenty of airflow. Voila, at least doubled trans life for less than $100.

that is an excellent idea...if you do add another cooler, plumb it so it runs through the new cooler first, then through the rad trans cooler, and back to the tranny...this will temper the fluid and keep warm fluid returning to the trans...

Dear desertmule,

Your admonition about pre-heating the ATF after it is cooled belies your name. This sounds like good advice for motorists above the Arctic circle.

An auxiliary external cooler does not make warm fluid cold, it just takes it down 20-30 degrees. With a starting temp above 200 degrees, the fluid is not taken below a safe operating range. The cooler just helps keep it from getting hot enough to break down and cause damage to friction surfaces, which dramatically shortens trans life.

that is an excellent idea...if you do add another cooler, plumb it so it runs through the new cooler first, then through the rad trans cooler, and back to the tranny...this will temper the fluid and keep warm fluid returning to the trans...

Plumbing it that way would be absolutely worthless! The fluid would be the same temp with or without the new cooler then. You have to plumb the new cooler in AFTER the factory trans cooler for it to have any benefit.

I always disconnect the lines to the factory pipe ("cooler") completely, relying on the aftermarket unit 100%. My 700R4's last 250,000 miles set up this way.

Our friend rksand needn't linit himself to replacement radiators wi the factory "cooler" provision. If I installed a new radiator with the hot water pipe, I wouldn't bother hooking it up, just bypass it from the start in favor of a more efficient air-to-coolant unit.

that is an excellent idea...if you do add another cooler, plumb it so it runs through the new cooler first, then through the rad trans cooler, and back to the tranny...this will temper the fluid and keep warm fluid returning to the trans...

I agree unless it never gets below somewhere around freezing where you live. The temperature at which transmission fluid begins to break down is 220 degrees fahrenheit. If you go to too low of a temp (don't remember the number), it can start to do damage too (not to the fluid, but the trans can slip). If you have a very small aux. cooler, you can probably get away with plumbing it either way. I use my truck only for off-roading, towing big trailers, etc. and my auxillary cooler is about half the size of the radiator. During the winter the outlet is not noticably warmer than the bumper, so I have it run back through the rad. cooler to get it warmed up a bit.

Where is the drain plug? I was told it was on the drivers side.
Looked for quit a while and couldn't find it.