Yanmar Transmission

[Nils Andersen]

I have a Hunter 27 with a Yanmar 8SB diesel.While motoring out of the marina the boat suddenly lost propulsion. The engine was still running, put the prop was obviously not turning anymore.After being towed back to my slip, I checked thatA: the prop was still there (although I don't know if it could be slipping)B: I could not see any movement of the prop shaft where it attaches to the transmission.1. What could be causing this?2. What is required to remove the transmission? Does the prop shaft have to be pulled?

 

[Bil Thomas Feng Shui]

Trans check

One of the first things to check is that the shift level/cable is engaging at the transmission. If your cable is broken it may have enganged the trans enough to get you moving and then popped out of gear and not allowing you to get it back in. Check the free and easy before jumping to pull the transmission. try an isolate possible problems. Then if it is determined that it is the trans, pull it. Tip: you can pull the trans in the water, the shaft down't come out. Just clamp a pair of hose clamps mid sharft so that when you release it from the trans it does not slide out and into your rudder.

 

[Howard]

Slip/Slop

The key here is that the slipping isn't to hard to fix, but it's pretty sloppy.I have had the same problem this year and it cut my season really short.I assume that you checked the shift cableand leaver to assure that the problem isn't that the cable isn't puching or pulling far enough. You can check by pulling the pin on the shift leaver and shifting by had. If after pulling or pushing thehandel right on the engine into forward or reverse and you still get no power to the prop the problem is probably a worn clutch plate.There are two clutch plates, a forward and a reverse. Usually the forward goes because you use it 95% of the time. But if you replace one do both at the same time they cost about $65 each.To replace them you have to drain the oil from the transmission. (Slopopy job)Then you seperate the shaft at the coupling. Then you unbolt the transbmission. Put a lot of paper and towels under it cause it will drip from the transmission. You then pull out clutch plate assembly. You put it on the bench and unbotl the plates. If you jhave the manual it's not too hart to see how it comes apart. You but it back together and voula....I don't remember if you have to pull off the shift leaver mechanism before you pull the transmission. If you don't have enough room to pull the transmittion you can try to drop the rudder to slide the shaft back a little father and if you still need more room you can take the flange off the shaft and slide it out completely.If you still don't have enough room you can lift the engine off of the mounts and either pull the engine or move it enough to pull the transmission off. It's thigh and messy but you can do it in the boat.If you do it yourself expect to pay about $200 in parts (remember the gaskets). It should take about 20 hours.If you have it doen expct to spent about $1000.But check the cable and shift leaver first. If you want to disciss it further email me at hnelson@downstate.com.