WhathaveIdone

Thank you, S-Prihadi. Very good information.
To conclude this experience, I wanted to show a post-mortem of the radiator and where it failed. Why is up for speculation. Metal failer from coolant? or just poor quality constr4uction in that end of the cooler?
The breach occurred at the borrow end of the trany cooler. See photos. It is clear that the metail was eteched away. See the erroded areas, the watch the dye come from the lower end (it will leak from each section if I filled it entirely)
The cooler itslef has no identification but the engine raidator was Valeo, made in France. The engine radiator itself appeared in good condition with no leaks!
Thanks to all who provided fantastic suggestiions.


Outlet tank with trany cooler installed

Outlet tank showing oil stains from trany oil

Trany cooler

Non breachend of trany cooler

Breached end of trany cooler

bmwpowere36m3

Looks like it eroded from the coolant side, no? That's wild, the factory spec coolant (most any modern) is meant to protect aluminum (assuming) that's what the AT cooler is made from. I wonder if those segments are soldered/brazed with a soft metal. I've heard certain coolant types provide poor protection against soft metals like lead and brass (common of older radiators).

S-Prihadi

Thank you so much OP.
You read my mind
I actually wanted to ask you to autopsy the radiator/trany-cooler combo core for more learning.
Very nice....