High whining sound on 3rd gear+ Def90 td5

Hi

I just got my Def90 TD5 back after a while in the workshop.
Water damage (engine recondition, electronics replaced).

The car is making a high whining noise when in 3rd gear+ and the revs are rising. Sounds like an airplane taking off.

Any ideas what it can be? As mentioned just got the car back after 2+ years and not looking forward to sending it to another workshop or the price that comes with it.

Additional info:
Not present in gear 1 or 2.
Not present on high revs in neutral.
Car also seems weaker (struggling with hills) - although this might be because of a few lost horses with the recondition.

Suspecting gearbox maybe.

Have you drained the oil from the gearbox to check the state of what comes out?

Propman said:

Have you drained the oil from the gearbox to check the state of what comes out?

Click to expand...

Yes - new oil - old oil was milky/watery

MariusJVH said:

Yes - new oil - old oil was milky/watery

Click to expand...

Sorry, I should have also included the transfer box.

Any hint of metal in the oil mix?

Does it cease when the clutch is depressed?

ouch! seals are probably shot, mine leaks as well not an issue but dont take it wading but will never wade with mine

could be the lack of lubricity due to water damage , try renewing the oil see what happens