Bolt torque specifications

[Lew Gato]

Does anyone know the torque specs for the nut that holds the pinion gear to the bottom of the driveshaft? Also the six bolts that hold the powerhead to the the upper casing. The motor is a 15 hp two stroke, 2018 E15DMHS.

Thanks
Lew

[99yam40]

I do not, but I do not own that model motor.
most people that work on their own motors get a service manual for their motor so they have all that info before working on it.

[boscoe99]

19 pound feet.

[boscoe99]

What did you find out about the crank shaft splines?

[Lew Gato]

Boscoe99... I pulled the powerhead and found out that the splines had not sheared. The driveshaft itself had broken about 3 inches from the top. A perfectly clean break. The top of the shaft was badly scored and both ends of the break were mushroomed as if beaten on with a hammer. The oil seal housing was totally corroded and the bottom part had broken off. My theory is that the housing was pressing on the shaft and causing it to bend. The constant flexing eventually caused it to break. I have seen this before on a badly aligned diesel engine. The 1 1/4 inch propeller shaft broke cleanly at the transmission coupling. The dealer here in Bonaire has never seen one fail in 30 years. I ordered a new shaft. It has to come from Japan and will be here in two months.

[Keithbaja]

I Seen that once in my 40+ YRs.
Do Not put grease on the very top of driveshaft when greasing the the splines. It doesn't compress and can do what your describe. You should also use Loctite RED on the pinion nut

[ausnoelm]

When did people start using poor English? Seen instead of has seen, have seen or saw? It's just so common now, but completely wrong.

[zenoahphobic]

Nothing to do with Yamaha, unexpectedly I had a wheel axle, that was bigger than the above, shear clean through. It was on the curb side of an F100, took the wheel completely off as the truck (ex ambulance) gradually ground to a halt. Brake backing plate was ground to half moon, and barely 1/4 inch from grinding the LPG tank had it gone further down the hill!
Lots of people were surprised to see a shaft that thick snap. But it was clear that the shaft was poorly manufactured with this fault line, and it was only a matter of time till it would fail.