knocking noise around gearbox on td5.

hi there..has anyone come across this before..whilst driving my discovery td5 all is good untill i get up to 5th gear..once im in 5th gear if i take my foot of the throtle i have a knocking noise coming from underneath which sounds like around gearbox area..as my disco slows down in 5th the noise gets slower too.but once i press throtle down the noise goes,but only happens in 5th..also noise goes if i press the clutch but once i relise clutch the noise is back untill i press throtle..has anyone got any ideas please before i start to take my gear box out..help.thanks for looking at this...mark.

I would recommend you get underneath and have a very GOOD look over the front propshaft, inparticular on the transfer box end where you will see a "double UJ" arrangement.

Check for wear / movement in all directions, ANY play is not good and will require either your shaft being rebuilt, or purchase of a new one.

will check that today and update you later..thanks for replying...mark.

This sounds like exactly the same noise I have, mine started in 5th only, now happens in all but 1st, I have had both Difs to bits and found nothing wrong, I have checked both props and cant find anything there either.
The noise is like the clicker on the wheel of fortune type wheel spinning and clicking faster as you speed up and then slows as you slow.
I am now driving untill it gets bad enough to show up, it would be good to hear from anyone who has any idea!

hi there again...where do i start...the noise is naw in every gear and even when its not in gear standing still..the noise sounds like its coming from the centre of the gearbox..has anyone got any ideas please.....

Hi there again,,want to say thanks to those that looked at my link and made any comments on my knocking noise around my gearbox..sorry its been a while but hope iv got it sorted naw so just to update my link..i pulled my gearbox out and stripped it down only to find both my fifth gear cogs had there teeth broken off in places and to find the bearing next to my fifth gear had nearly come apart..rollers in the bearing had managed to move to its side so it would not work proparly..found another 2 of the rollers in the box casing..so 2 new fifth gear cogs and a full bearing kit..box back together..but got new issue to look at before i refit box...rear crank seal..any one done one latly..put new one on but still leaks..not even started my disco.leave it on ramp over night and new sign of oil drips on floor in morning..any ideas please.....thanks all....mark..

Was it a genuine seal or some aftermarket sh*t?....when it's about gaskets or seals use only genuine ones.....happened to me, i had to remove the sump again after i've replaced the gasket with an aftermarket one which leaked worst than the old one.