Water in auto gearbox oil - Gunky brown

[stellagetsmewasted]

Hi all. Just purchased a 320i convertible for a very small price as I identified the head gasket had gone which I am in the process of replacing now. I did also notice that the dip stick for the auto box showed that the auto box oil was the same light brown cream that you get in the header tank on a head gasket problem (ooof)

The car was left sitting about for a couple of years so could this just be condensation ingress or how else could the water penetrate the auto box please? also would a flush and replace sort this out or is the fact that water has been in there ruined the box?

Cheers for any help

[swinster]

I would drain, change the filter and replace with nice new ATF. As the car has been sitting for a while a full fluid change wouldn't go amiss.

[stellagetsmewasted]

Cheers I will drain and change filter but does anyone know how the water could have got into the oil in the first place?

Also is there a method for draining the torque converter oil as I dont want it to mix with new oil and be back to square A1 again.

Thanks

[swinster]

Maybe water has got there through time, condensation and lack of use.

You could replace the oil strainer and pan, start the car and get more ATF out or just replace with new ATF the amount is insignificant that is left in the torque converter.
A regular change at a later date might be a good idea like in 6 or 12 months, which is way before the recommended time 24 months.
Have you also changed all the other fluids like power steering and coolant, and filter change. All will be a bonus to get her running back up to spec a BMW is for life and not just for easter!! They can go on forever with the correct TLC.

[pacerpete]

There are several ways water can get in an autobox, the most common being the cooler in the radiator leaking into the rad and visa versa . Water will damage auto trans components so the problem/cause needs to be adressed asap.

[jaistanley]

I assume water is more likely to go from the coolant system to the autobox system due to the pressure the coolant system runs at? If not you could check the coolant for traces of autobox oil to help diagnose possibly?

Just a thought.