Driveshaft won’t engage powerhead

[Hamboat Captham]

I have a 2015 yam 9.9t just got going. Wad working great for a few shifts then started making noise when I got back to neutral. The shaft spins if you put it into gear and spin the prop but it doesn’t lockup to the powerhead. Whatever catches it in the powerhead isn’t working it seems like. Pulled the leg and the splines look good, clean with no broken bits stuck to the grease. Thanks

[walleye1]

Make sure your shift shaft is hooked up, the two nuts, one long one and a short one.

[boscoe99]

Prior to the removing the lower unit was the motor placed into reverse gear and then left that way the entire time? And when the lower unit was removed was the shift shaft left in the reverse position the entire time?

[Hamboat Captham]

Not sure if it was in reverse gear the whole time before removal. Not really fowllowing that. I did put it in reverse to get the shift shafts apart. Then into neutral to take the locknut off. The leg mates up fine. The shaft goes into the powerhead but it’s not engaging it seems

[Hamboat Captham]

I had shifted forward and reverse a few times , i might have slipped past neutral on the last shift. I’m guessing the drive shaft slides right into the end of the crank?

[boscoe99]

Presumption is that it is a model T9.9.

I don't think your problem is with the drive shaft. My guess is that the shift cam assy is out of sync with the shift rod.

Modus operandi is to shift the motor into reverse. Just barely loosen the jam nut and then turn the coupling nut until the shift rod separates from the shift cam assy. Remove the lower unit. Service the water pump taking care that the shift rod and the shift cam assy are not allowed to move.

Reinstall the lower unit. Screw the coupling nut down to join the shift rod to the shift cam assy. Tighten the jam nut.

If these procedures are not followed, and the shift cam or shift rod are allowed to move before the lower unit is installed, the motor may be difficult or impossible to shift correctly.

[Hamboat Captham]

Thanks bos, that’s what happened I’m sure, yup 9.9t . seemed like I almost got it to engage when I was putting the leg on and off to try and figure out the problem. That’s a new one to me. So is there any way to fix this or is the shift can fried?

[panasonic]

This engine new to you? You say your just got it going and it started making noise from the gearbox after shifting a few times and this all happened BEFORE the LU was dropped?

Sounds like the shift linkage was not just right in the first place and now it is even worse since you had it off and back on again.

If not the linkage....then something may be wrong in the gearbox itself.

[Hamboat Captham]

Yup, new to me. Had it apart before cleaned and everything and grease it up. Gearbox is fine as far as I can tell, it locks up when shifted and spins the shaft. Sounded like it’s coming from topside, thought the timing belt had jumped a tooth at first, driveshaft stripped? If you pop it in gear it spins the shaft which you can see going into the powerhead.

I tried to put it back on with everything set to reverse. Didn’t work. I had shifted it with it pulled from the power head which messed the shift cam it looks like, not sure. Guessing it’s up there in the powerhead? It acts like the driveshaft is stripped, but it’s clean and neat. It’s not grabbing though

[Hamboat Captham]

Ran and shifted fine in the tank, put a new water pump on, strapped it to the boat ran and shifted fine, then didn’t

[panasonic]

If the splines in the driveshaft socket on the bottom of the powerhead were stripped out and you could hear it skipping on the driveshaft then there would be damage to the mating splines on top of the driveshaft, wouldnt you think?

I would drop the lower unit again, look at the splines in the bottom of the powerhead see if they are damaged.

When you had the LU off before, to replace the Water pump, did you remove the shift shaft assy from the LU for some reason?

Also do you have a service manual for this engine? And can you post the exact model and serial number located on the transom bracket.

[Hamboat Captham]

Thanks pana, yup no damage on the splines. Why I thought there was something up in the powerhead that wasn’t mating. I’m just assuming that it slides into the crank like most do. Didn’t touch the shift shaft assembly at all. Goes into gear fine on the leg, spins the shaft and gears engage solid.

The noise is a whir not a grind, had the leg on and off a few times since, slides up into the crankshaft as usual, once you find the spline alignment. Makes me think there’s some safety up topside not doing its thing. Bos mentioned the shift cam?

I do have a factory service manual but it looks like it might be the 06 or so generation. Kind of useless for a lot of things it seems like. Standard poor diagrams and partial procedures. Pretty close though. I don’t have the numbers but could get those in the am. It’s the long shaft with power tilt and electric start, remote cables 703 control box.


Thanks again

[FabricGATOR]

The water pump is turned by the main drive shaft. I did not hear you say he water pump was not working either.... so I deduce that is not really happening.

Remember, both the forward and the reverse gear are turning all the time. When you shift an engine lower unit, you are simply directing the prop shaft to either grab the 'always turning' forward gear or to grab the 'always turning' reverse gear.

I say you got your shift linkage out of wonk and the gear selector dogs are not fully engaging properly.
Now the fact that it worked twice and then broke... I am having a hard time understanding or imagining that/

[Hamboat Captham]

I was hoping for the simple fix like linkage adjustment. If you disconnect the linkage and shift by hand (pliers) same thing. I removed the leg to test the shifting right at the box (leg). Shifts great as always, nice and firm into gear and locked to the shaft. Lots of water from the new pump works great . Worked about 5 times, then I think I slipped past neutral on a shift. I hadn’t mounted the control box and was trying to hold it for testing.

The thing that gets me is the drive shaft that goes through the exhaust housing and mates up to the powerhead is spinning and locked when shifted into gear seen through the slot just below the powerhead, If you turn the prop by hand. Should be locked to the crankshaft at that point. Neutral still freewheeles smooth as silk. Nice smooth shifts same as always, solidly in gear.

Hard to beleive it’s broken too but here we are and I can’t find anything messed up or broken, that’s why I asked here, thought there was a trick I was missing, but it did work those few times. Maybe I’ll run it with the leg off for a second to see if the noise is gone.

[99yam40]

I was hoping for the simple fix like linkage adjustment. If you disconnect the linkage and shift by hand (pliers) same thing. I removed the leg to test the shifting right at the box (leg). Shifts great as always, nice and firm into gear and locked to the shaft. Lots of water from the new pump works great . Worked about 5 times, then I think I slipped past neutral on a shift. I hadn’t mounted the control box and was trying to hold it for testing.

The thing that gets me is the drive shaft that goes through the exhaust housing and mates up to the powerhead is spinning and locked when shifted into gear seen through the slot just below the powerhead, If you turn the prop by hand. Should be locked to the crankshaft at that point. Neutral still freewheeles smooth as silk. Nice smooth shifts same as always, solidly in gear.

Hard to beleive it’s broken too but here we are and I can’t find anything messed up or broken, that’s why I asked here, thought there was a trick I was missing, but it did work those few times. Maybe I’ll run it with the leg off for a second to see if the noise is gone.

I am having a hard time understanding what you are saying in the bold.
are you saying the drive shaft turns freely when in gear and you turn the prop shaft even when the lower unit is mounted on the motor?

the drive shaft should only turn when the crank shaft is turning