Tohatsu 9.8 2006 rock problem

[seattl]

backed into a hidden rock with my 2006 Tohatsu 9.8 4-stroke. Prop was damaged but engine re-started ok and it carried me home, however, at the top end it suddenly stops pushing. Seems like it hesitates and there is no more power. If I cut the rpm's back then it will start to push again. Any ideas?

Thanks - very new to outboard motors so all advice is welcomed!!

 

[TGuy]

Re: Tohatsu 9.8 2006 rock problem

sounds like you spun the hub in the prop. The prop has a hub in the center that's designed to give away if you hit a rock (to reduce the impact and minimize damage to the gears, shaft, etc). Once the hub has been "spun" off the prop, it will hold at lower speeds but at higher speeds the prop spins faster than the hub and doesn't "grap" so you lose power. Most prop shops can fix it although I don't know how cost effective it is on a small prop like that. Might be cheaper to just buy a new prop??

 

[TOHATSU GURU]

Re: Tohatsu 9.8 2006 rock problem

It's the prop and I don't think anyone offers a hub for that one, so a new one is in your future.

 

[seattl]

Re: Tohatsu 9.8 2006 rock problem

strange thing is that when I removed the prop the nut was only finger tight - didn't need a wrench to loosen it, so I guess it was being held on by the split pin...

It's the prop and I don't think anyone offers a hub for that one, so a new one is in your future.

 

[TOHATSU GURU]

Re: Tohatsu 9.8 2006 rock problem

The nut is usually not that tight as the pin keeps it in place. But, hand tight is a little more loose than normal. Probably a result of the impact slamming the prop back against the washer/nut.

 

[halfmoa]

Re: Tohatsu 9.8 2006 rock problem

The nut is usually not that tight as the pin keeps it in place. But, hand tight is a little more loose than normal. Probably a result of the impact slamming the prop back against the washer/nut.

^^^It wasn't a Tohatsu motor but that nut tightness scenario happened to a friend and I in just that situation.

 

[pvanv]

Re: Tohatsu 9.8 2006 rock problem

The MFS8/9.8A3 (year is unimportant, model is everything), has a splined prop hub, so as long as the nut is at least finger-tight, the cotter retains the nut, and the nut threads retain the brass splines onto the shaft. Not a big deal, though I like them tighter. A loose nut will not allow the prop to slip. 99.9% chance the hub is spun. You can get a new prop from any dealer. If your performance was good, reaching near max WOT RPM, stick with the same pitch... if not, this is the time to get a different pitch, that puts you closer to optimum WOT RPM.