Slipping out of gear when speeding up

[Kirkie]

My 1993 Larson Mercruiser 3.0 runs great until I start to accelerate to plan, it feels and sounds like it slips out of gear. When I pull the accelerator back, it goes back into gear.

 

[alldodge]

Probably spun the coupler or prop hub
When was the last time the alignment was checked?

 

[Kirkie]

Probably spun the coupler or prop hub
When was the last time the alignment was checked?

It came out of the shop last fall.

 

[Kirkie]

This the second time the boat has been in the water since. I believe it had this problem the first time, but the water was rough and I did not try to put it on plan.

 

[alldodge]

It came out of the shop last fall.

What did the shop do?

If they changed the lube and impeller they may or may not have checked alignment

Did you smell burnt rubber when it lost power?

Go to the prop and use mark the prop and nut with with grease pencil, splash of paint or other method. Take boat for another run and then recheck to see if prop moved.

If prop doesn't move, pull drive and check coupler

 

[airshot]

It came out of the shop last fall.

That doesn't say much....what all did the shop do ?? You should have an itemized bill !!

 

[QBhoy]

Odds on to be the prop hub sacrificed itself. Would be the usual cause.

 

[Kirkie]

What did the shop do?

If they changed the lube and impeller they may or may not have checked alignment

Did you smell burnt rubber when it lost power?

Go to the prop and use mark the prop and nut with with grease pencil, splash of paint or other method. Take boat for another run and then recheck to see if prop moved.

If prop doesn't move, pull drive and check coupler

I will try to take the boat out soon, bad weather. I did find that the lower unit was very low on oil.
There was no oil smell on the previous trip. I will do your suggestion before the boat gets wet again.

 

[Texasmark]

In marking the prop mark a straight line from the ID Spline to the OD barrel of the prop. If the line is not still straight after testing, hub is slipping....just clarifying a suggestion above so that the line connects the right places.

On the slippage, I know not the history of your usage habits but I have had the Forward gear sawtooth gears (drive and driven) develop rounded corners rather than designed sharp corners somewhat like a saw blade. With a weak clutch dog spring (the thing around the prop shaft that moves back and forth to select the desired gear) when you put power to the prop shaft, the original vertical portions of the gears are no longer straight vertical, but rounded on the tips and they can't stay meshed.....hammer down on it and it slipped; back off and it worked fine.....had this problem on a '65 110 HP Mercruiser boat I bought, well used.....er ah well abused. Buying that thing is a story in itself....half sunk in a marina but just had to have that Starcraft at the time and paid way too much for what it was.

 

[Scott Danforth]

I will try to take the boat out soon, bad weather. I did find that the lower unit was very low on oil.
There was no oil smell on the previous trip. I will do your suggestion before the boat gets wet again.

I would check the alignment and check if it's compromised.