Just done an oil change on my MTX75 box and the old oil looks milky which I am led to believe means water contamination.

The car previously blew a gearbox when I bought it which was then replaced by the used-car dealer. I'm assuming that this water ingress could be the reason for the previous gearbox failure.

Does anyone know any common problems or things to check on these that could cause water ingress? (Mk2.5 1.8TDCi)

I've attached a picture...

stupid screen wash jets - rain leaks by - the right one fills the engine around the spark plugs with 2 litres of water - the left pours water all over the ignition coil pack - where is the gearbox breather directly under this water fall ?

or do you frequently end up driving in deep puddles

if none of that applies

a) short runs and it never gets a chance to burn of normal condensation build up
b) other interesting design to pour coolant in to destroy the box I'm not yet aware of (would expect this on later better engineered cars - where 'designed to fail' is in full 'flood')