Well, I'm back.
Tranny fluid found leaking from the front out of he flywheel inspection hole. No signs of transmission fluid cooler lines or the cooler leaking or damaged.
Coolant in radiator surprisingly clear -- may have been changed along he way. No signs of cross contamination with transmission fluid.
Transmission drained. Maybe 1 quart left. Didn't bother measuring. Not good. Decided at this point to NOT drop the pan, as the owner and I did not see he point of throwing money at it for a filter, gasket, and new pan bots. Not until we had SOME indication this transmission actually wanted to and could go back into gear. Even a hint.
This was the NASTIEST used transmission fluid I have ever seen in my life. Deep dark cloudy thick black//brown fluid. Had to be the original fluid.
IMHO, BMW was obviously "setting up" their customers for 1 transmission replacement during the life of the vehicle. To have a transmission (auto) last much above 150k mi with regular transmission service is pretty good. But if the fluid is any indication, this transmission is on borrowed time after 100K if the lifetime fill is left undisturbed.
In an attempt to get some of this disgusting fluid out and replace it with something functional (Valvoline Max life , met spec for the 325Z transmission -- right on the label.) Did two drain and fills, shifting gears after each one to circulate fluid -- but because the gears were not engaging, I suspect this was not actually occurring.
When I did the second drain, it looked pretty much like the first -- maybe a lighter dark brown, It was at this point that I realized the red fluid we were trying to drain n fill was not really mixing with the existing nasty fluid. Additionally, the liquid was coming out of the fill hole as pure clear red, another indication that there was no real mixing occurring.
The pump inside the transmission was making awful groaning sounds like a dry pump does. We shut it down.
Semi-conclusion: Pump failure and possibly other seal failure, allowing transmission fluid to leak out the front of the transmission. Seal disintegration may have scattered debris throughout the whole system. Pan drop would verify that, but irrelevant right now.
Swapping in a used transmission is probably not as costly as diagnosing this one and then rebuilding. The problem is, you don't know what you are getting in a used transmission--is it as abused from neglect as the one that just failed?
I am trying to convince the owners to sell it as a running engine/nice interior dent free exterior with decent paint---
-- + income from failure vs unknown transplant cost
-- unknown reliability of the used tranny--unless it has been fully rebuilt already.
Don't know how much a good engine/blown tranny goes for in USD . Any guestimates?
Thanks to all for your guidance on this. I received a total of ZERO responses or suggestions on two US based BMW forums
The typical US BMW owner does not have nor want knowledge of how the car works. They just want it to run. Until it fails. Then take it to the Stealership to overpay for repairs.
The owner of this BMW is DIYer and happily bucks the trend. But it will all be for naught.
Thanks again.
Derf