Noises from the rear diff on a TD5

Hi there

I have a strange noise coming from my rear diff. If I have been driving forwards and then stop to reverse, as I lift the clutch in reverse and apply torque in the opposite direction through the diff, it makes one loud knock. I can then reverse quite happily without anymore noises. Until - I go forward again, and it makes the same loud click - once. It appears to have 2 "states" - forward and reverse - and it makes a loud noise each time is changes state.

I can also make it click if I drop a gear and let the clutch up too fast.

So for 99% of the time, it's no problem but as soon as I initially change direction, or make a jolty gear change, it makes a loud click.

I can recreate it by rocking the vehicle back and forward when parked, and it makes the loud metalic click as it rocks back and forward. Using a screwdriver to transmit sound to my ear I know it is the diff.

Does anyone have any ideas what this could be?

2 other things that might be related:
- I've just noticed the oil seal has sprung a leak
- I had a horrible shrill squeaking noise about a month ago which sounded like it was coming from the rear diff at about 50mph. It stopped after about 5 miles and has not been back in over 1000 miles. Weird!

I'm confused!!

Ta

Sounds like the drive flange is worn or loose and moving on its splines which would also cause the oil seal to leak over time.

Thanks Shifty

What's the easiest way to test this? Take off the prop shaft and see if there's any play in the flange and/or whether the nut is done up properly?

you can check it with prop on ,put box in neutral with hand brake off ,check rotationally as well as up/down there should be no up/down play at all ,and if your careful you will feel were excess play if any is rotationally

What JM says.

Thanks Gents

Right - I've got a fair amount of rotational play but none lengthways as per the video. Is this normal or is this excessive? Feels a bit much (to my untrained eye!)

IMG_0306.MOV - YouTube

if your gentle enough you can feel whether its in crown wheel /pinion or diff ,its not a hard job to fix once diffs out for competent diyer with instruction

I have disconnected the prop shaft with the intention of making the play easier to diagnose.The only problem is I don't know what to feel for! I think the play is made up of 2 halves - the first half feels free - then it engages something - and the second half feels like something else is turning inside.

I might be imagining it though!

Would this contribute to my loud clicking noise when moving forward or backwards the first time after driving in the opposite direction?