Vanishing Terminal Sounding Gearbox Noise???

[ScottyDave]

Ok got a weird one...
First off I had the clutch changed last july on my 2 ltr hdi 90 rapier and everything was fine then in november some idiot backs a pickup into the ns rear quarter, no probs insurance job. The day before its due to go to repairers I come home to her in doors saying the cars making a funny noise
Out to the car and holy sh*t sounds like armmagedon in reverse, first and second akin to a ball bearing being thrown into a washing machine on full spin 3rd was quiet, anyway the car gets recovered to repairers for the body work and we go away for the newyear.
When we come home the car is sitting on the drive looking good I decided to start it up and... the noise is GONE went for a drive and nothing everything was fine as it should be.
I then thought maybe a bolt that had come loose from the clutch change had caused the noise and had been shaken out of the way when on the recovery truck...
That was till a fortnight ago when it returned so last weekend I put it up on the ramps to drain the gear oil ( sloping drive so car ends up level ) to check for the expected bits of metal, it comes out CLEAN however I didn't get much more than 200ml out of it should be about 1.9 ltrs I think. Underneath has been well sprayed with oil so the driveshaft seal must have gone.
Anyway with the oil topped up the noise has gone and the car drives perfectly again.

Could the lack of oil been the cause?? what could it be?

Its now going in tomorrow to have the seal done.

Thanks for any feedback, Dave

[Captain Jack]

Any gearbox noises are treated with some new gearbox oil before anything else, so it could well have been it.

[Doggy]

Aux. belt bottom pulleys can make a humungous noise, then go quiet again for a bit - worth checking.

[ScottyDave]

Worth checking round the pulleys I suppose, although I'm pretty certain its the gearbox side of things as it was disappearing in 3rd gear and returning in 1st, 2nd & rev. Been surgested it might be a failing synchomesh?
Its having the driveshaft seals done now to see if the lack of oil was the cause which won't have helped any

[Captain Jack]

406 gearboxes are normally pretty tough, not much goes wrong with them.

[Gary406]

you should have around 2 litres of oil in there

so you only getting 200ml out of it sounds to me like you found your problem

200ml

are they doing both seals ?

[ScottyDave]

Yeah both seals done. Got car back now, garage said to keep an eye out for any fresh drops over the weekend, then settle the bill on Monday so fingers crossed it stopped leaking and with oil in the box theres no more noises...