Shaft not engaging powerhead

[Captham]

got a 2015 yam 9.9t I just got going, was working great for a few shifts, then started making a whirring noise. Checked it out , shaft spins but doesn’t engage the power head anymore it looks like. Put it in gear and spin the prop by hand, spins the shaft, can see it where I goes through the upper case spinning, no resistance from the motor, not locked in. Pulled the leg, splines look good, no marks, no shavings or anything.

Has anyone ever had or heard of this problem?

thanks

 

[racerone]

Pull the lower unit apart.-----I think perhaps the driveshaft sheared at the pinion gear.

 

[Captham]

Thanks for the response race, don’t think that’s the problem. In gear the driveshaft spins and is locked to the prop shaft. In neutral the prop free wheels disengaged from the drive shaft. With the leg installed if you put it in gear and spin the prop the driveshaft spins you can see through the peep hole, with the motor off when you do this you can not turn the prop as it’s locked to the engine in gear, usually. But the shaft is spinning in the crank it seems.

it’s like the crank sheared, but the splines look clean and unmarked, no shavings or evidence of a break. The noise was a whirring sound, not a grind or crunch. I might run it with the leg off for a second to see if the noise is gone. I have a feeling with the leg on the water pump won’t be going if that shaft isn’t being turned by the crank

 

[racerone]

Running around in circles won't help.-----Take the power head off and inspect the spline.-----Or take powerhead apart to inspect the crankshaft.

 

[Captham]

Thanks again racer, I was really trying to avoid that!! It’s a 4 stroker so I’d have to separate the oil pan. Also handing off the back of our sailboat 3 foot down. Was hoping for the easy fix, something I did wrong when I changed the pump. Shear pin, crank insert? Don’t know. New things are so tricky and fragile these days, it’s only 3 years and a couple days out of warranty, like it was meant to fail. I’ll do a couple more tests and see what’s new today before I yank it.

 

[racerone]

Tried another prop ?------Maybe the rubber hub is slipping ?----Have you looked at shift adjustment ?

 

[Captham]

Ya I checked those, when I put it in gear it locks the driveshaft, which spins up in the powerhead instead of locking. Thought there might be a neutral safety up in there

 

[Captham]

Somebody had mentioned the correct procedure was to shift both into reverse and keep it that way the whole tome or you can bigger your shift cam and it won’t work right, but it shifts fine and locks the shaft

 

[racerone]

Good luck with it.

 

[Captham]

Thanks, wrenched it up on deck and standing on the boom gallows. Going to rip it down in the am. Thought there might be something coupling the two but it looks like the regular driveshaft into the crankshaft, supposed to be anyway from everyone I’ve talked to.

 

[Captham]

Pulled the powerhead, bad crank snout. Anyone know it an earlier gen crankshaft will fit? The 90 something to 06? It’s a 2015, yam, 9.9t 4stroker

 

[racerone]

Drastic failure for such a " quality " motor.-----Sounds like the Yamaha factory should help.-----Unless of course it has hundreds of hrs on it.-----Do you know the history of this motor ?

 

[Captham]

“Hundreds”!!?? Sounds like it’s reached it’s limits if that’s all she’s got in her!!

Single owner, kept maintainance up, he definitely used it. Looks brand new though and everything else works great. Might have a few hundred already but not sure, was on a sailboat so it’s an in out the harbor kind of thing. Wasn’t impressed with the thin walled brass water tube, thought they fixed that from their earlier runs, starting to disentigrate. I know it was major problems on their bit motors.

Was dealer serviced always if that says anything. They must have known and cleaned out the snout when they did the water pump. Where did all the metal go?? They convienently don’t have the service records anymore. They also said 1yr warranty on their small motors, I thought it was a standard 3 across the board. The driveshaft looks perfect for some reason.