Black transmission oil

[shemandr]

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It has the a bouquet of red raspberries with a hint of grass and pencil shavings...oops, that's the wine that I'm drinking. -- Geoff

What no Mocha Gelato?

 

[Steve Dion]

Geoff:

Here is the specs for the Yanmar transmissions for your review.

http://yanmarhelp.com/i_box2.htm

I think I would flush it out after running for an hour or two so you know that it is clean before you start your evaluation.

Normally old transmission oil is just darkened after a hundred hours or so.

 

[Gunni]

I do sail with the engine in gear to keep the prop from free-wheeling. I have a 3 blade max-prop. Should I have it in forward or reverse or doesn't it matter?
-- Geoff

Reverse. In forward, your shaft will turn, just slowly as it damages your transmission. If you stop your engine and leave it in forward your Max-Prop will not feather, it continues to turn with the flow and grinds your transmission cones against a stopped engine flywheel. But don't believe me, go search Yanmar and their Kansaki service bulletins. This is why any buyer should require an oil analysis as part of their survey.

 

[Benny17441]

What does the oil smell like? Also, flush the tranny with a cup or so of new oil and put it in a glass jar. Let it sit for a few hours and check for sediment. You can then pour off the oil on top and feel the sediment.
Engine hours and tranny hours are NOT the same. Tranny hours would also include all that time in neutral while sailing and the prop is spinning. Yanmar recommends this BTW. I would not be worried with the 1000 tranny hours between changes as the oil is not seeing combustion products.

It is true what Bill indicates, the oil in the transmission is enclosed in a sealed environment and not subjected to contamination by combustion residues. I do have one caveat about not worrying about 1,000 hours between changes and that is that oil is more degraded by the effects of heat than by suspended contaminants. I would be fine with a 1,000 hours if I included those spent freewheeling and if I used a synthetic oil which is much more heat resistant and can longer maintain adequate viscosity. In any case periodic checks for oil level and viscosity should more closely indicate when it is time to change the tranny oil. Just wipe the oil from the stick between your thumb and forefinger and you will be able to feel how slippery and thick a healthy oil feels. If it smells burnt, changes color, feels too thin and allows friction then it is past the time to replace.

 

[kloudie1]

Goeff.. That is good news.. Sounds like new oil, run it a few hours, then new oil again and change it at 250 hours or less. My official Yanmar manual has 250 as the change interval. As was previously stated, after engine shutdown under sail, go to reverse to stop the propeller so that it can feather; because your prop feathers, leaving it in reverse will not harm anything.. leaving it in forward can prematurely wear the clutch cone. Yanmar recommends neutral with a conventional propeller. Sounds like your black oil is a result of old age and some hard use.. probably did no measurable harm to the box..

 

[Scott B]

My Yanmar manual states 250 hours OR 1 year. 2005 3YM30 with KM2P marine gear.

 

[geoffschultz]

My Yanmar manual states 250 hours OR 1 year. 2005 3YM30 with KM2P marine gear.

I guess that's the difference between a 1998 Yanmar 3JH2-TBE with a KM3A and yours. However, I've changed my maintenance schedule to reflect this much shorter interval.

Thanks to all of you for your useful feedback!

-- Geoff