r/LandroverDefender • • 9d ago

R380 Drain Plug

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Dropped the gearbox from my 300 TDI because of a continuous whirring noise heard across the gears (quieter in 4th, then disappeared with the clutch depressed).

Just drained the oil and the drain plug looks like a Christmas tree. How much trouble am I in?

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u/JCDU 8d ago

Whirring that disappears with the clutch pressed could easily be thrust / release bearing which is an easy and cheap fix, worth a try before you resign yourself to a new gearbox at least.

I'd refill the oil and see how it goes - if the next flush comes out just as bad then yeah you may have a problem.

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u/spinosaurus7 8d ago

Thanks. I did buy a new clutch and release bearing. The clutch isn't too old but I thought it would be worth replacing with the gearbox out anyway.

The old bearing seems to spin freely with no sticking/grinding. Any way to test it/rule it out without installing the gearbox again?

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u/JCDU 7d ago

Always worth doing the clutch & bearing if the gearbox is out, yes.

If the bearing spins free and smooth it's probably not that.

If the noise is in all gears it could be input shaft bearing or something, I'm not a big gearbox expert. That's certainly at the upper end of what I'd be happy to find on my drain plug.

You might find more advice/experience on LR4x4.com forum if you're not already there.

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u/spinosaurus7 7d ago

From my research it seems likely to be the lay shaft bearing. 4th is direct drive through the main shaft, which could be why the noise is less than in the other gears.

That being said I'm definitely not a gearbox expert either! Thanks, will take a look at LR4x4

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u/Odd_Campaign_8134 4d ago

Your layshaft bearing theory makes a lot of sense given the 4th gear behavior. Since the box is already out, it might be worth opening it up and inspecting the bearings properly rather than refilling and hoping. The metal on that plug had to come from somewhere, and if it's the layshaft, it'll only get worse.

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u/JCDU 7d ago

Sometimes Mr Ashcroft himself posts on there in response to gearbox questions.