I have a 1996 Defender with the 300TDI.
i was off road and submerged the truck. The engine stoped once it dipped to low in the water. Once the truck was removed from the water, the air cleaner and filter was removed and water drained from the air intake pipes. the engine was turned over in short rotations to push the water out. the engine started and ran fine with lots of power, although lost of initial white smoke.
the oil was changed, air filter renewed, gas tank drained and refilled. Now on cold starts it smokes and when driven for the first 1/2k the smell is very Diesel and white smoke.
after the 1/2 k drive, and i am out of my nieghbourhood, it runs fine.