H27 transmission problems

[Gary Cyr]

My H27 is a great boat when there is even light wind. But a poor preformer under power. When motoring is needed due to no wind it barely moves. In foreward at 700-800 rpm it moves just ok, but an increase to 900-1100 rpm there is no increase in speed, in fact in does not move at all sometimes. One day we were becalmed on our return from a weekend cruise in newport,ri to fall river,ma. just 14 miles. I turned the boat around and ran for 2 hrs in reverseto make 2 knots, in foward we drifted backwards against the tide. I would welcome any suggestions.gary cyr garycyr@prodigy.net

 

[Mike Birch]

gears, prop, compression?

Just guessing here and I suppose you have already done that but sometimes brainstorming can spark and idea that leads to a diagnosis.If you can reverse but not go forward I guess the most obvious thing is forward gear.Maybe first gear is badly worn or missing teeth? Are you sure forward gear always actually engages?Have you checked the prop? Even a visual inspection may not be good enough. Is it the correct prop for your year and motor? Is it misshaped, chipped, badly corroded. I do not have the same problem but as regular maintenance I had my prop checked and straightened last year, ~$75 for diver to remove it and replace it a week a part and I took it to a local prop shop for the work which was ~$90. This probably does not hold up too well with reverse being OK.Does the motor rev reasonably freely, can you sustain 2500 rpm without any overheating? When was the motor last serviced, oil change compression check, pumps serviced etc.? Once again this probably does not hold up too well with reverse being OK.Good luck

 

[Tom M]

The check list that grows

First gary, what kind of engine do you have? how come you can't get 2800 to 3000 rpms in neutral or in gear, and if os is there any vibration and at what rpm or rpms does it vibrate ? check list: is your water pumping a steady flow of water? does your exhaust pump out a lot of black smoke ? is exhaust hose unobstructed ? do you add a additive in your fuel,? do you always top off you fuel tank ? what about your fuel filters ? have you unhooked the line between fuel enjector pump and the enjector to see if the pump is functioning correct ? have you changed the fuel filter on the engine, if it gets cloged you will not get the rpms needed, same as a worn out cam lobe that drives the enjector pump, have you checked the cables for full function capability, if their loose, no fuel ! I don't want to overwhelm you so I'll end my list, there are a lot of items that can limit the flow of fuel, but before I'd go tearing out my transmission, and if all things fail to be successful go pull out your fuel enjector and have it tested by a proffecional.

 

[Anthony Trupiano]

H27 Transmission Problem reply

Gary,When I first bought my H27 in '97 I had the same problem the first time out. I quickly determined it to be transmission trouble, since the Yanmar 1GM engine ran flawlessly and was well maintained. Due to lack of support from local marinas, I decided to give it a go myself. I pulled the transmission, which took about an hour in very awkward positions, and began tearing it down. I found the tranny to be a lot less complex than I had thought. With the manual in one hand and a wrench in the other, it took about 2 hours to disassemble, clean, and determine the problem. It turns out that the only mechanism which engages both forward and reverse gears is a tappered bushing about 2" around and 3" long which has, or is supposed to have ridges around its circumference. Once these ridges wear, which was the case in my transmission, the loss of friction between this bushing and the internal bore of either the forward or reverse gear cases this bushing to spin freely and transmit low or no power at all. Once I replaced this bushing (a $200 item) and re-assembled the transmission it ran great!! It has been two years now since this simple rebuild and I still have oodles of power. For $200 and a few hours of your time, it is well worth it.