Series 3 Sudden Gearbox Noises - Any Guesses?

I know there are many treads here about noisy gearboxes but I haven't been able to find a thread which references my particular symptoms - I am hoping that some kind soul more knowledgeable than myself will be able to help.

I run a 1978 Series 3 LWB Truck Cab with petrol 2.25 engine and overdrive.

For a number of months 4th gear has been a little noisy but only when accelerating - a type of 'handful of gravel in the tumble dryer" type of noise, nothing overly noisy but enough to hear quite clearly. All other gears are fine including reverse. I have no problems selecting any gear nor any problems with jumping out of gear.

The other night out in the Landy all of a sudden the gearbox started making a very loud 'clacking' type noise which made me pull to the side of the road. This noise seems to be present in all forward gears (havent checked reverse) whether I am accelerating or not. The Landy still drives fine in every gear and gear selection is still ok and there is no jumping out of gear either - it's just this loud clacking noise.

I didnt want to use it just in case I further damaged it and got toed home. When being toed with the engine on and in neutral the clacking noise was still present.

Any ideas guys?
Many thanks.

jack a front and rear wheel up in turn and feel and rotate diffs and props to try to ascertain whether its box or something in the drive train

I had a similar loud clacking noise which got worse the faster I drove in my 1977 lwb. It was a UJ.

Col

Could be a collapsed main shaft bearing although I would expect difficulty selecting gears in that case. Because 4th gear is direct, it is usually much quieter than the other three so you hear other noises more clearly, like UJ's and T-box whine.

jamesmartin said:

jack a front and rear wheel up in turn and feel and rotate diffs and props to try to ascertain whether its box or something in the drive train

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Many thanks jamesmartin. Got some time Tuesday so will investigate then. Fingers crossed!

Colthebrummie said:

I had a similar loud clacking noise which got worse the faster I drove in my 1977 lwb. It was a UJ.

Col

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Hopefully it will be a UJ instead of the gearbox. Many thanks Colthebrummie.

Erubus said:

Could be a collapsed main shaft bearing although I would expect difficulty selecting gears in that case. Because 4th gear is direct, it is usually much quieter than the other three so you hear other noises more clearly, like UJ's and T-box whine.

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Many thanks Erubus.

I kind of like noisy parts. The difficulty is when you fix them you can hear all the other problems.

Worth finding out where it's coming from though and make sure it's not a bycycle jammed between the gearbox and tunnel. I hate it when that happens.

If you put the transfer box in neutral, fire it up and select the gears in turn, you can have a listen to the main box on its own. Might help to narrow the field down a bit.

My money is on a uj though. Sounds like somebody whacking the gearbox with a spanner!

I have a magnet in the gearbox drain plug so if all else fails I hope to catch some bits to see what is playing up. Hope its the UJ!

rob1miles said:

I have a magnet in the gearbox drain plug so if all else fails I hope to catch some bits to see what is playing up. Hope its the UJ!

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Hi Rob, appreciate this was a few years ago, yet I have the very exact symptoms. Sounds like clanking or tapping on the transfer case. Spent today stripping down to get the box out. That's next weekend. Anyway, what was your issue? UJ or gearbox.

Caelan said:

Many thanks jamesmartin. Got some time Tuesday so will investigate then. Fingers crossed!

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Hi Caelen, what was the issue - was it a UJ joint? I have some new clanking from the bellhousing, sounds like someone is clanking it with a spanner! Stripped it all down to get the box out neext weekend - many thanks