M1123 transmission issues

[kingConan]

Hi there,
I haven't been on here for a bit. I had a transmission issue with my 4L80E, and it appears that water has gotten into it. Long story short, had it rebuilt and ready to install. I still cannot figure out how anything got into the transmission other than an issue with the transmission/engine oil cooler. My question is, can a different cooler work on these? The OEM ones are spendy! It looks like a basic GM setup with horizontal tubes and different sections for the oil and transmission. Any suggestions would be appreciated!

 

[williamh]

Doesn’t it have a separate transmission cooler ?
are you loosing antifreeze ? Was water leaking from the lines while the transmission was out ? You could do a pressure test on the cooler , put about 80psi on it and see if it dropped after a while. I don’t see why you couldn’t add or replace the cooler with an aftermarket one. Been doing it for decades on regular cars.

 

[Mogman]

The trans cooler has nothing to do with the coolant, the radiator is completely separate.