So, I pulled the trans cooler lines off the rad this morning. I hosed the cooler out with brake clean, then followed up with blowing it out with compressed air. I capped off one end of the cooler, and put a nipple on the other end. I connected a vacuum pump and drew down to 30 lbs of vacuum. \

Then I pulled the radiator cap, confirmed the rad was full of coolant, then put a pressure tester on the cooling system and pumped up 14 lbs of pressure, while the vacuum was on the trans cooler. I let it sit for more then an hour, both gauges never changed. Would that have been long enough to show a problem? I would have thought that with pressure on the cooling system and vacuum on the cooler, if something was bad, it should have shown up in an hour, right? How long is long enough?

I'm going to move forward under the assumption that the water got into the trans during its improper storage before it got installed in my truck.I'm going to have the system flushed at a local shop. I'm paranoid enough now that I'm adding an outside trans cooler and will plug off the trans cooler in the radiator. When the truck makes it to the road, I will check to see if there is antifreeze in the trans cooler, then proceed with a radiator claim if needed then. The Rad has a "lifetime guarantee". By then, I should also know how the trans has survived the ordeal. Gene

put press on the rad and leave the cooler lines open and see if water comes out.

Sounds like you tested the cooler/radiator correctly and found no leaks.

I’d move on.

Drop the pan, break the valve body loose which will help drain half the converter.
Pull the accumulator out to drain behind it, with the valve body still loose stroke the front and rear servos to purge them of fluid.

Blow the lines. Hook everything up and add the cheapest trans fluid you can buy and run it on the stand - wheels off the ground through all the gears. Don’t drive it.

After running it for a bit wing the engine a few times to help mix the fluid in the converter.
Shut the engine down.
Remove the rear cooler line from the trans.
Place in a large bucket and have someone start the engine and place in drive. Run it until the fluid flow starts to diminish, do not run it longer than that - then shut it down.

Drop the pan and break the valve body loose again as above then reassemble.
Add your fluid and you should be good. If you are still worried perform the drain procedure one more time.

The biggest risk from coolant in the trans is it eats up the bonding agent for the clutch discs and bands.

Transman has a good idea. I think you've already verified that the radiator isn't leaking into the built-in trans cooler

I dropped the truck off at the shop tonight that will flush the trans. I've known the guys at that shop since we were both in school. They will treat me right and do a good job. I do welding for them, and they do the mechanical stuff I can't or don't want to do. Its a good trade off.

My shop is an active welding shop. Its not the place to have a trans apart, even for a day. I also have no way of containing that much trans fluid. Doing it myself is a disaster waiting to happen, a guy has to know his limitations.

I want to thank everyone for their help. I will do an update when the truck rolls down the road, hopefully in a couple of months. Gene

Because you have water in it.

$342 later, I now have the proper color of ATF. They had to flush it 2x to get it cleaned up (and they used the ATF +4 both times). The few block drive home was not long enough to tell how the trans fared.

Moving on. I have lights, interior, bumpers, tires, and glass to install before I can give it a proper road test. I will update when I can really drive it. Gene

That's what i figured was going to have to be done in one of my earlier replies to this posting.
Been there, done that.
Used those flushing machines, when i was a full time, wrenching mechanic, for a living.