OK, so it's not good to have water and antifreeze in the transmission.

The problem, as I understand it, is that when you drain the ATF you only
get a portion of the fluid out of the transmission; the rest stays in the
torque converter.

Does that mean I should have the entire transmission taken apart and all,
every last drop, of the old (and now contaminated) ATF cleaned out? That
would be expensive and worth doing only if the alternative is certain
damage to the tranny.

I've already been having collateral problems with the transmission. After
the new cooler had been installed and everything flushed out, I took the
van out for a trip. On our first climb up into the mountains (north of
Phoenix), the transmission started leaking. I'ts been suggested that what
happened was that the coolant still in the system turned to steam and
created enough pressure to blow one or more seals. Is this just a preview
of problems to come?

Mark Pry
1990 GL