I have a Yanmar SB8 with a Japanese export Transmission in a 1978 Hunter 27. It will go into reverse just fine but neutral is a bit flaky and forward is not soled. It seems to slips really bad. I have had this boat about two weeks now, so I do not know a lot about it and this is my first boat with an inboard. After my last trip to take it out for a spine and finding out that it really has no forward I found that the trasmission is way over full. I read that this transmission leaks engine oil into the transmission and the oil had an off color to it like ‘coffee with cream’. There is no water-cooling to the transmission and the engine oil is not tinted. The oil was just changed by a service tech, could he have over filled it or is it the leaking seal. Could the extra oil make it not go into forward gear?
Yanmar SB8 Transmission
- Thread starter Roger10073
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Engin oil in transmission?
Well if it is a Yanmar engine I find it pretty hard to believe that engine oil is leaking into the transmission. I know of no engine except some motorcycle engine/transmissions that has the ability to leak into the transmission as the flywheel is on the "outside" of the engine and the transmission connects to the "even more outside" side of the flywheel. The engine oil is kept inside the engine by a shaft seal that is on the engine side of the flywheel. To leak engine oil into the transmission the oil would have to make it past the engine shaft seal, down the crankcase rear end, up the transmission front end and through the transmission front shaft seal. Impossible! Other (non standard) transmission oiling means Does the transmission have an oil line from the engine? I've never seen this but I've not seen everything either. Coffee with cream is water in the oil and churned by the gears. This is bad! Does the transmission have a cooling system (most don't)? If yes this is most likely the source of the water. If no then the only thing I can think of is the transmission has a breather (I did not see one in the picture. It would look like a fitting on the top somewhere) and the transmission has been under water where the breather did its job and let the outside get inside. As for no forward gear, just overfilling the transmission will not cause the gear to not operate. It could be that gear selector ring has one side of its' bearing surface gone or the gears could be stripped. Either is going to require a tear down to inspect it repair it. The hard part of the tear down is getting the transmission out of and back into the boat. The actual transmission is simplicity itself and well with in the abilities of anybody who can change the oil on their car. What noises does the transmission make in reverse, neutral, and forward? How does the shift linkage "feel" when you are shifting it, soft, hard, clunky, grinding? These are the things inquiring mind want to know. Sorry I don't have better news but at least it is free.
Well if it is a Yanmar engine I find it pretty hard to believe that engine oil is leaking into the transmission. I know of no engine except some motorcycle engine/transmissions that has the ability to leak into the transmission as the flywheel is on the "outside" of the engine and the transmission connects to the "even more outside" side of the flywheel. The engine oil is kept inside the engine by a shaft seal that is on the engine side of the flywheel. To leak engine oil into the transmission the oil would have to make it past the engine shaft seal, down the crankcase rear end, up the transmission front end and through the transmission front shaft seal. Impossible! Other (non standard) transmission oiling means Does the transmission have an oil line from the engine? I've never seen this but I've not seen everything either. Coffee with cream is water in the oil and churned by the gears. This is bad! Does the transmission have a cooling system (most don't)? If yes this is most likely the source of the water. If no then the only thing I can think of is the transmission has a breather (I did not see one in the picture. It would look like a fitting on the top somewhere) and the transmission has been under water where the breather did its job and let the outside get inside. As for no forward gear, just overfilling the transmission will not cause the gear to not operate. It could be that gear selector ring has one side of its' bearing surface gone or the gears could be stripped. Either is going to require a tear down to inspect it repair it. The hard part of the tear down is getting the transmission out of and back into the boat. The actual transmission is simplicity itself and well with in the abilities of anybody who can change the oil on their car. What noises does the transmission make in reverse, neutral, and forward? How does the shift linkage "feel" when you are shifting it, soft, hard, clunky, grinding? These are the things inquiring mind want to know. Sorry I don't have better news but at least it is free.
Bill did you see that shift lever?
Just like those old Hurths. I had one on my Atomic four. The whole thing was a dinosaur. Horrible. Looks like that old Yanmar might have been a copy of one of those old manual boxes. And my old tranny shared its' oil with the engine crankcase. There was no bulkhead between the two. Did I say 'horrible design' yet? And the worst part of the design, the worst ever created by man (next to an Espar heater) was that the 4 cylinder engine had only TWO main bearings! Yep, my crank broke in Canada.
Just like those old Hurths. I had one on my Atomic four. The whole thing was a dinosaur. Horrible. Looks like that old Yanmar might have been a copy of one of those old manual boxes. And my old tranny shared its' oil with the engine crankcase. There was no bulkhead between the two. Did I say 'horrible design' yet? And the worst part of the design, the worst ever created by man (next to an Espar heater) was that the 4 cylinder engine had only TWO main bearings! Yep, my crank broke in Canada.
Engine and tranny sharing oil
Yea Fred that shift lever is certainly high tech. That must be the manual back up in case the cable breaks. AND you can use your car tire iron in a pinch. I'd buy off on the engine and tranny sharing oil except Roger indicated that the engine oil was OK while the tranny oil was coffee w/cream. I'll bet that if he looks around in the engine spaces he can find evidence of a "high water mark". That kind of event is real hard to hide. Roger Does the boat have a manual for the transmission? That and a description of the "feel" of the shift lever as you use it could go a long way to diagnosing the problem.
Yea Fred that shift lever is certainly high tech. That must be the manual back up in case the cable breaks. AND you can use your car tire iron in a pinch. I'd buy off on the engine and tranny sharing oil except Roger indicated that the engine oil was OK while the tranny oil was coffee w/cream. I'll bet that if he looks around in the engine spaces he can find evidence of a "high water mark". That kind of event is real hard to hide. Roger Does the boat have a manual for the transmission? That and a description of the "feel" of the shift lever as you use it could go a long way to diagnosing the problem.
Hard shifting?
I had a similar problem with my '82 Hunter 27. I had trouble shifting after it got warm. I discovered the same thing, water in with the oil. I drained it and put in fresh oil, ran it a bit and then replaced it again. After about three times, the oil stayed good and the shifting problem went away. It seems to be a pretty forgiving transmission because I certainly abused it.
I had a similar problem with my '82 Hunter 27. I had trouble shifting after it got warm. I discovered the same thing, water in with the oil. I drained it and put in fresh oil, ran it a bit and then replaced it again. After about three times, the oil stayed good and the shifting problem went away. It seems to be a pretty forgiving transmission because I certainly abused it.
Take a look at the manual
Roger, Its not a normal transmission, but I guess they work OK - (28 years seems pretty good.) If you post your email address I can send the shop manual if needed on Monday. FYI, I pulled my YSB8 (with trany) out and replaced it with a 2YM15 - I had the YSB posted for sale on this site with no takers, let me know if you might be interested. Randy
Roger, Its not a normal transmission, but I guess they work OK - (28 years seems pretty good.) If you post your email address I can send the shop manual if needed on Monday. FYI, I pulled my YSB8 (with trany) out and replaced it with a 2YM15 - I had the YSB posted for sale on this site with no takers, let me know if you might be interested. Randy
check the manual
Some of the transmissions take engine oil. Some take automatic transmission fluid. I have a Hurth transmission and it takes ATM. The engine manual should contain a section on the transmission. (It may contain more than one section if the engine routinely shipped with different transmissions. Be sure you have the right section of the manual for your transmission.)
Some of the transmissions take engine oil. Some take automatic transmission fluid. I have a Hurth transmission and it takes ATM. The engine manual should contain a section on the transmission. (It may contain more than one section if the engine routinely shipped with different transmissions. Be sure you have the right section of the manual for your transmission.)
Debra...
they all take ATM! LOL! Yours takes ATF, but you need to be more specific as there are two major types, F and Dexron. Dexron is the common ATF used in boat applications (F is Ford's and Dexron's is GM's). It's not good to mix 'em.
they all take ATM! LOL! Yours takes ATF, but you need to be more specific as there are two major types, F and Dexron. Dexron is the common ATF used in boat applications (F is Ford's and Dexron's is GM's). It's not good to mix 'em.
ATM... ATF both are probably required...
You can see where my mind is at. I don't remember the type of ATF... but it is in the manual. (You have to have an engine manual!)
You can see where my mind is at. I don't remember the type of ATF... but it is in the manual. (You have to have an engine manual!)
Take a look at the manual
*cry Randy I do not have a manual for ether the SB8 or the Trany. The boat has no manuals at all. My email address is ka7bge@comcast.net.nospam Remove all after ‘net’. I have researched the net a lot and I am very sure that the trany do’s not take ATM ATF or any other kind of transmission oil. It only takes 30-weight motor oil. Roger
*cry Randy I do not have a manual for ether the SB8 or the Trany. The boat has no manuals at all. My email address is ka7bge@comcast.net.nospam Remove all after ‘net’. I have researched the net a lot and I am very sure that the trany do’s not take ATM ATF or any other kind of transmission oil. It only takes 30-weight motor oil. Roger
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