Yanmar GM10 gearbox whine

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Sailing steve

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Yanmar GM10 gearbox develops a distinct gear whine once the oil is hot in both ahead and astern but it's quiet in neutral. Engine is over twenty years old with a good maintenance history but no record of hours run.

Gearbox oil is clean and up to the full mark on the dipstick with no signs of debris. It's a new boat to me - should I be concerned or can anybody say if some whine is normal with this gearbox? Thank you.
 
About all you can do, short of a major strip-down, is to change the oil, making sure the new stuff is the correct spec. which I can't remember. As it's in both drive directions, it's unlikely to be the output shaft bearing and I don't think it's particularly "normal", I'm a bit surprised you can hear much above the noise of a 1GM.
 
There's definitely a whine when it's hot.

I don't know which oil the gearbox has in it at the moment - conflicting sources suggest it should be either a SAE 30 monograde or a 15W/40 mineral - which is the same oil that's been used in the engine in the past.
 
It should be 30 weight single grade. Or 20 weight where it’s really really cold.

Multi grade oils don’t generally go in gearboxes though there’s always an exception!

whine.....it’s not prop singing?
 
Sailing steve said:
Yanmar GM10 gearbox develops a distinct gear whine once the oil is hot in both ahead and astern but it's quiet in neutral. Engine is over twenty years old with a good maintenance history but no record of hours run.

Gearbox oil is clean and up to the full mark on the dipstick with no signs of debris. It's a new boat to me - should I be concerned or can anybody say if some whine is normal with this gearbox? Thank you.
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In neutral the box isnt turning so why would you not expect the noise to be different? All gearboxes whine to some degree - they have that in common with the Remainers on this forum. :ROFLMAO: Maybe you dont expect it because your car has such effective sound deadening.

Personally I wouldnt worry. The gearbox is a small one, easily removed and taken apart, and you have the boat anyway. I once flew back from Spain with its bigger brother from a "GM in my cabin luggage. My problem was the cone clutch and it was quickly and cheaply repaired by Cellar marine in Cornwall.
 
A mate of mine had a 1GM much older than mine. His had a definite whine. Mine didn’t. The older 1GM ran for years despite the whine.
 
It's the only GM10 I've ever heard running and only for a few hours so can't really have a feel for if it's right or not. Going to change the oil to be sure it's the right product in the 'box - once I find out what that is - and will run it a bit more and see.

Thanks everybody. (y)
 
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