Black residue in transmission

[waltnebula]

I noticed black residue on my transmission dipstick. The boat was not used or cleaned during Covid time and the prop accumulated a growth of oysters. I previously recently ran the boat for two hours during which it was very sluggish and would not get up to normal speed. The Yanmar 4JH3 was run at 2800 during which the boat speed was 4-5 knots rather than its normal 6.5-7. I think the trans may have been slipping during this period and wore some material off the plates. After the prop was cleaned the boat ran OK but the fluid has a reddish tinge.

Obviously it needs a fluid change, but is there anything else that should be done to avoid further damage? Should the engine be run in neutral befaore the fluid change? Is there a filter in the trans that needs to be cleaned or changed? Any information would be helpful.

 

[Ted]

You should probably have the fluid in the transmission professionally analyzed. The report you receive will give you a good idea about what's in that fluid and if it's normal or harmful. Do it on a regular schedule and keep track of any changes between tests. It could prevent a major repair down the road.

 

[jssailem]

It could prevent a major repair down the road.

Or at least let you know when something is going wrong.

 

[Benny17441]

A fouled prop increases the load on the engine and transmission. It can lead to engine and transmission overheating if operated for long periods of time. The engine has a cooling system, but the transmission is mainly cooled by its fluid. The biggest enemy of oil and transmission fluids is heat. I understood that you have not replaced transmission fluid in at least two years (covid). It could very well be that age degraded fluid, was subject to added friction and heat which could have broken viscosity down leaving a charred by-product. I would change the fluid right away and use a Full Synthetic Fluid which will provide added protection against heat breakdown. Make sure the prop is clean and the boat's bottom is clean and try the boat out. Yanmar transmissions are pretty hardy and if the boat is running fine there is not likely any damage. Minor vibrations may not be a transmission problem but prop changes in balance as a result of the scraping of heavy growth.

 

[dlochner]

ATF is red. If it has any black or maroon color the transmission probably needs to be rebuilt and have the cones replaced, especially if it is slipping. The proper ATF for the Kanzaki or ZF transmissions is Dextron III usually labeled for older vehicles. The newer formulations are too slippery and will impregnate the cones causing slippage.

 

[Tally Ho]

ATF is red. If it has any black or maroon color the transmission probably needs to be rebuilt and have the cones replaced, especially if it is slipping. The proper ATF for the Kanzaki or ZF transmissions is Dextron III usually labeled for older vehicles. The newer formulations are too slippery and will impregnate the cones causing slippage.

My Kanzaki transmission uses engine oil.

Greg

 

[JamesG161]

Mine is a Synthetic Oil per Owner's Manual.

I changed mine to higher Viscosity Oil, used by Highway Diesel Truck type, after this picture of my oil.



Jim...

PS: My transmission is water cooled when engine is running.

 

[kloudie1]

Just a couple of quick clarifying notes:
there are two different kinds of Kanzaki gearboxes in the older Hunters with Yanmar engines. One has cone clutches and the other has multiplate friction disk clutches.. The cone type generally should have straight engine oil and the plate type should have ATF in them. The KM 2 and 3 have cone clutches and use motor oil. The KBW gearboxes used on some of the higher HP engines have multiplate clutches and should use ATF.
I am not familiar with the gearboxes used on the Universal diesels bit I have not seen one that called for engine oil.. there may be some, but I haven'tr seen one..
Best advice is to positively identify your particular gearbox and go with their recommendations.

 

[Ralph Johnstone]

Best advice is to positively identify your particular gearbox and go with their recommendations.

There are a couple of Xmission postings floating around the site right now in which the owner does not know the make of their transmission and yet is looking for wild speculation as to what they should dump into said Xmission. @kloudie1 's mantra (or similar idea) always seems to pop up in these discussions but is pretty much ignored . This recommendation is based on the manufacturer's information.
THERE CAN BE NO OTHER RECOMMENDATION.

Can anyone here explain why, on a boat, the more expensive the piece of equipment, the more likely the owner is to rely on information which does not come from the manufacturer's literature and furthermore, may cause expensive damage ?