And this week's breakdown is.....

[jozg44]

THE GEARBOX!

Any thoughts on this-

My gearbox (standard Series III 4-speed, later 'C' type) has started making a low drone/growl/whine noise in 3rd and 4th gears. It is particularly noticeable under load (accelerating, going up hills), is quieter on the flat or at a steady speed and practically disappears when coasting downhill. There is no noise in 1st and 2nd, and the noise disappears above about 45 mph.

It seems to be that I've got a faulty bearing somewhere, but which one?

This is not a good time for this to happen . I spent all of Monday changing every drop of oil in the engine/gearboxes and axles, greasing all the UJs and flushing out the brakes and hydraulics after I lent the SIII to someone to do some light on-road towing, and it came back with mud splattered up to the roof Apparently they decided to take a 'short cut' and it ended up stuck in a pond over its wheel rims for an hour.

Anyway, ranting over- any help appreciated as ever.

Jack

[Series 3 guy]

Jozg- Not sure man! If it was up to it's floorboards there might be a good chance that the noise you hear may not be your your gearbox! Check the inside of those size 16 rims and check for excessive mud build up.The noise and or vibrations WILL travel noise-wise throgh your gearbox as your speed increases making it sond like the gearbox is going.I had a set of Bridgestone muds and my indy guy was convinced the noise they made was my box going out.Check it out mate and good luck!!!

[antichrist]

Since it appears to only do it under load it could well be wear on the gear teeth. Though that would probably start with little noise and get louder as the wrear increased. Was there any water in the gear oil when you drained it? It could also be, as mentioned, something not even in your gearbox, but I wouldn't expect that to only appear under load. Have you tried putting the transfer box in neutral and running it in 3rd and 4th to see if you can still hear it?