Recently replace my knackered gearbox on my ducato 2.3 multijet to find 100 miles later it makes the most terrible noise in reverse it was a second hand unit supposedly 'reconditioned'

Any clues about how to solve this problem ?

If it's a reconditioned gearbox, then regardless of the problem its best to let the vendor replace it under warranty, otherwise it could cost a small fortune to fix.

Assuming you have the MLGU6 gearbox, the reverse gear and shaft appears to be at the top of the engine, maybe a little more oil,

(1) driving gear (6 nd).
(2) synchronizer(5rd/6th speeds).
(3) driving gear(5th gear).
(4) driving gear(4th gear).
(5) gearbox casing.
(6) driving gear(3rd gear).
(7) driving gear(2nd gear).
( 8)Reverse gear shaft.
( 9)Reverse gear motor pinion.
(10)Reverse gear .
(11)1 st gear motor pinion.
(12) clutch bell housing.
(13) input shaft.
(14) output shaft.
( 15)Differential crown wheel.
(16) planet wheels.
(17) sun wheels.
( 18)Differential housing.
( 19)Planet wheels shaft.
(20) driven gear(1st gear).
(21) 1st/2nd synchronizer and reverse driven gear.
(22) driven gear(2nd gear).
(23) driven gear(3rd gear).
(24) 3rd/4th synchronizer.
(25) driven gear(4th gear).
(26) driven gear(5th gear).
(27) driven gear (6th).
(28)6 th gear cover.
( 29)Secondary shaft screw.
( 30)Primary shaft screw.

As a new user well chuffed with quick and usefull response! Will try more oil in the morning as that would be most obvious place to start. I would return but as bought on ebay i only had 14 days too complain! Diagram is great couldn't find one on internet atall might dismantle old box and compare the two now i know what im looking at!

Mine sounds like a bag of nails if the reverse isn't engaged fully - usually when the wife is driving cables might need tweaking. How much did you put in ,recommended is 2.5l - 2.7l to ensure adequate 5th gear lubrication

Worse than a bag of nails more like a bag of ducks being strangled. i put in the same as the amount that came out will try in a small amount at a time

Minimum that should have come out is around 2l. With ebay you can claim up to 5days if you paid with paypal. Even if not its worth ringing him and saying hey pal the box is duff worst that can happen is he tells you to f off.

Most companies I've used on ebay offer a warranty on reconditioned items such as gearboxes and engines.

meant 45days for ebay

Will try contacting them about it as more oil has not sorted the problem thanks for The help will keep you all updated!!

Got to be rebuilt again as a local precision garage recons its been put back together wrong and causing the gear shafts to 'float' around inside :/

On plus side the seller is paying the bill!

Its good to see it's getting sorted.

Finally sorted! the reverse gear idler was chipped on several teeth looks like it had seen two world wars! Now sorted and running smoothly again!