Or water getting in through the vent tube is a possibility.

 

Yep, a 99 has separate coolers from radiator. Just as puzzled as y'all are.

 

well i will check the vent tubes. make sure it is positioned correctly to prevent easy water ingress and then try draining and refill. The fluid that i put in when i did the work about 3-4 years ago was pennzoil ATF, clear red. Had a LR indy shop replace the XYZ switch gasket about 2.5 years ago though. we will see.

 

thats where I would start. Since the coolers are independent, you either have a vent tube that is allowing water to come in some how. Have you been in any water lately?

 

There is a diagram for the breather tube. It looks like the connection is just above the drivers side transmission mount and just loops back to itself. I know they always say the North American vehicles are not made to cross water higher than the center cap on the rim due to that breather tube. Hope the diagram helps you find the issue.

 

The trans cooler is the lower cooler in front of the rad.

This is why I change my fluid every year. Imo the trans is the most overlooked part of your vehicle that needs maintenance.

There are two lines, one from the top of the trans that goes to the driver side of the cooler, and the other comes from the bottom of the trans and goes to the passenger side of the cooler.

Two places to pay attention to, where the line enters and exits the cooler, this corrodes, making removal and installation of the lines a royal pain. You pull the plastic collar back till it's flush with the lip on the metal collar, then pull. To install the line, put something behind the aluminum cooler line or you can break the aluminum line off the cooler.

The other part of the line to pay attention to is where the rubber part gets crimped onto the steel line, that crimp can weaken and the rubber line will slide off thus spilling fluid out in less than 30 seconds and leave you stranded.

 

Ok, so I finally got around to draining the transmission fluid. Drained and refilled with Pennzoil ATF. That is what I put in last time I serviced the transmission.
At one point since I did the last fluid filter change the pan was leaking. Cleaned and refit one time and it really didn't help. Also had the XYZ switch seal by a shop about 2 1/2 years ago.

The fluid I drained off was the same as before, milky pink. I put it in a clear bottle and will check back on it in a couple of days to see if is separates. I ran the vehicle for about 1/2 hours or so running it through the gears and then drained the fluid off again. Same thick pink fluid. Now I proceeded to pull the pan and install a new filter and more fresh fluid. I noticed water beads around the inside lip of the pan when I was cleaning it out. Lots of grey film in the pan. I cleaned every thing off installed a new filter & gasket and refilled the transmission with Lubro Moly ATF. As I was filling the transmission, the overflow that was coming back out was not clear pink but milky still. Haven't had a chance to take it for a drive but will do that tomorrow.

I still don't know how water/moisture got in the transmission. I checked the breather lines and they seem ok. Can really see the connection to the transmission but could feel it. Both breathers for the transmission and transferase are in the engine bay fire wall area, There is a shorter one and one that loops back onto the top of the transmission.

Any one have any more suggestions/comments.