Yanmar Gearbox with no oil - any advice on next steps

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picardy

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My 20hp Yanmar was fitted new with a shaft drive into my boat (not by a Yanmar dealer) this spring and after 3hrs use (3 x 1 hr sessions on different days) I decided to check all fluids. The gear box oil appears empty or at best very very low.

I have tried to suck it out with a syringe to inspect and only a minute amount of black oil was found.

I have obviously now ordered the correct Yanmar oil but what damage might have been done? In terms of next steps, I was going to fill the gearbox with correct oil, run it for a few mins and then change the oil and refill. Should I be doing anything else?

It was working fine with no noises / vibration etc

Many thanks
 
There is a drain plug on the gearbox. From memory the quantity is ~0.25 litres so not a lot. The level is measured with the dip stick screwed in and barely touches the end of the tube. New engine should have come with an instruction book!
 
Thanks yes I have the book - my concern is what damage might have been caused with almost no oil after 3hrs use and whether I should be doing anything else.
 
awol said:
There is a drain plug on the gearbox. From memory the quantity is ~0.25 litres so not a lot. The level is measured with the dip stick screwed in and barely touches the end of the tube. New engine should have come with an instruction book!
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The level should be checked without screwing the dipstick in.

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picardy said:
Thanks yes I have the book - my concern is what damage might have been caused with almost no oil after 3hrs use and whether I should be doing anything else.
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If there was not enough oil in there to lubricate all the moving parts and especially as the oil you found was black the only way to be sure everything is Ok is to completely dismantle the box and inspect all the gears and bearings.
 
My gearbox oil is clear, I'd be removing yours and doing what @VicS suggests. Then looking for the people who fitted it and asking them some pointy questions.

P.S. WOBBLE should include your gearbox.
 
Without trying to sound cynical - it’s done now, it had some oil in, I wouldn’t dismantle it (more risk of messing it up), the clutch cones probably had enough oil thrown on to them (but if not - what are you going to do now? You wouldn’t want to open your wallet big time unless/until it fails - so keep it filled from now with fresh oil and hope for the best.
 
My Bukh 20 gearbox lost its oil on a few occasions, it sometimes whined a bit after running for a while before I discovered the problem.

Still good today, I transferred it to my Bukh 24 replacement.

If this box wasn't noisy, I'd be hoping no harm done.
 
Thank you all - I think I'll just see how it goes and change the oil a couple of times as its such a small quantity anyway - I assume there isn't an oil filter / magnet that collects any swarf?
 
I seem to recall that in the past one would use castrol solvent flushing oil in the engine when doing oil changes to flush the engine out. Would this have the same effect on a gear box if it was filled & run for 20 mins then drained to draw any swarf into the bottom of the sump?
That being said, if there was oil still in the box it should still be OK & best option is to run it & monitor performance over time
 
VicS said:
There is confusion about this.
The extracts I posted came from a 2019 edition of the manual.
The 2007 edition says to fully reinsert the dipstick
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I suspect the level is not critical otherwise the dipstick would be more easily readable. As long as the bottom of the gears are in oil then it will be fine. If there really was no oil I would be looking for its escape route or having words with the installer. From memory my new 3ym20 engine and box were empty but had obviously had oil previously.
 
Daydream believer said:
I seem to recall that in the past one would use castrol solvent flushing oil in the engine when doing oil changes to flush the engine out. Would this have the same effect on a gear box if it was filled & run for 20 mins then drained to draw any swarf into the bottom of the sump?
That being said, if there was oil still in the box it should still be OK & best option is to run it & monitor performance over time
Click to expand...
Cheap supermarket or leftover (fresh!) oil at roughly the right spec can be good for a quick ‘flush run’
 
dankilb said:
Cheap supermarket or leftover (fresh!) oil at roughly the right spec can be good for a quick ‘flush run’
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Flushing oil is a different sytem altogether. It is a detergent oil usually used on engines for removal of sludge, rust, carbon deposits ,etc. Cheap oil does not have the same effect. So that is why I wondered if anyone could comment on its use in gearboxes. . However, having researched it on google, it seems that flushing oil IS used to flush manual gearboxes.
 
After a leak caused water over the floorboards, my Yanmar 2GM gearbox had roughly 50/50 oil/saltwater.
I wasn't aware of the little vent on the dipstick that let the water in and merrily motored along for 50 or so hours until the service came up when the yuck was flushed and replaced. Still going. Be of good cheer.
 
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