Quote Originally Posted by Warwick89 View Post
So after many days the only information I have is that:
1. The radiator has been pulled and pressure tested and is completely fine and nil leak in cooler.
2. Everyone I've spoken to has the same opinion that the only other possible way it could happen would be submersion in a water crossing.

On that note the closest the patrol has come to water in the last few months is a high pressure hose. Could this do something?
Very possible, high pressure washing can cause lots of problems if one is not careful, I'm lead 2 believe the breathers are mounted inside the LH guard on GU's, did you pressure wash anywhere near where your gearbox breather is located?