Very alarming noise at 'high' speed

Well, high for a 2.25D S3!

On the motorway today at about 50 mph (not flat out but nearly there) and suddenly there's this loud noise which I can only describe as 'clack clack' repeated quite fast. Initially thought it sounded like it was trying to slip into 4WD so pulled over and engaged and disengaged the boxes but it started again as soon as we moved off again. Don't think it's engine noise as it stopped when not moving but with the engine sill running. Pulled off the m-way onto slower roads and did a bit of green lanes and it stopped and hasn't started again, even at 50 mph.

Any ideas guys?

Joe

Did you check underneath? Could be something stuck in a prop shaft or a stone wedged somewhere that spins...which has now fell off.

Sounds like it could be speed related vibration. 50mph is really pushing one of these old diesel girls, yes they will go faster but my Series 3 diesel is much happier at 45/48 cruise.
Have a waggle on the prop shafts and check to see if the hand brake on the back of the gear box is not a bit loose. Mine makes differing noises every day but they usually go away!
Good job they do it is my daily. Has it got free wheeling hubs? If so how long since they where looked at ? I have superwinch ones that are supposed to be greased every 4000 miles. Reallity is they get greased when the hubs are looked at for other work.

Dry UJ getting hot and seizing up,quiet again when cooled down or needle bearings wearing thin and falling out.Not much life left before prop comes apart if this is the case.

Just a wee tip when checking the UJs: if it's under any tension from the drive train, it can be very difficult to detect play. I'd chock the wheels on one side of her, transfer box in neutral and jack opposide rear wheel up.
At least UJs are cheap and reasonably easy to change.

High speed?
I got up to 40 mph the other day