'87 Mercruiser alpha one - transmission shifts into gear prop does not turn

[rjmc]

I live 2oo mi. from boat location, so have not yet seen personally. Family member was using boat last weekend. All was fine. He pulled into resturant dock for a while. When leaving he noted that he could hear the 'click' of the transmission shifting into gear, but boat would not move. Not sure if prop is spinning at idle only or not spinning at all. Shifting into forward or reverse gives same result. Any input you have is appreciated. Thanks.

 

[Texasmark]

Re: '87 Mercruiser alpha one - transmission shifts into gear prop does not turn

Not good news from here. First, did he look to see if he still had a prop?

If he lost his prop nut and his first gear selected after dining was R then he could have spun his prop off the shaft and it is now at the bottom of the water where he docked.

On the other hand, if the crooks are active in that area, like SCUBA type crooks, they may have helped themselves to his prop while he was dining.

Otherwise it doesn't make sense that all is fine and all of a sudden you have this immense problem.

Sorry for the news (my opinion of course)

Mark

 

[misterme21960]

Re: '87 Mercruiser alpha one - transmission shifts into gear prop does not turn

Ha, I was fishing the other day boat was running fine...decided to float and fish so I turned the engine off with NO problems...fished for 30 minutes started the motor back up and it wouldn't go anywhere forward or backwards...and it does make a NON motor noise when the engine is running...not real bad but I can hear it...

With boat out of the water engine OFF, I put the boat in gear and can only turn prop one direction in either forward or reverse which I assume is right...and in neutral it spins freely...shift linkages seem to work properly never had a problem with this boat EVER and I take care of it...

Inside the Engine compartment you could eat off it, clean, and the boat is a 1988 Larson with a 4.3L Mercruiser and Alpha One Outdrive...This boat has never been beat on or misused and NO one has ever drove it but me...all the fluids are clean and fresh...all the cables that run the throttle and linkage were new 4 years ago...and until this year the boat has only been out maybe 10 times since 2008...

Funny thing is there was never even a sign of any problems until I started it up that last time...Engine would rev but wouldn't move in the water...Thinking it could be that coupler in the bell housing, but wouldn't the prop turn freely even if it was in gear, Engine off...if it was that coupler?...

Another idea of my own is where the cable attaches to the outdrive from the throttle, since the from what I see the linkage moves when I operate the throttle...Also thought the prop, so I took it off and gonna put on my spare in the morning...but I'm thinkin' if it was the prop it would still move just alittle bit in gear if the center was spinning...Any ideas so I don't have to take it to a shop, not only do I not trust any shops...But I don't believe in what they charge to work on anything for the quality of work, I can do it myself with online and book knowledge...It isn't that difficult...and I can do about anything...And these boat forums are awesome, I would love to hear any ideas and if I'm heading in the right direction with this before I put the boat up this winter

 

[Texasmark]

Re: '87 Mercruiser alpha one - transmission shifts into gear prop does not turn

Confusing.

Agree that if you had a coupler problem you could freely spin the prop with the engine off. Really there aren't any couplers per se. You have spline linkage the whole way and in horizontal part of the outdrive you have a "constant velocity" joint that allows you to deliver power to the lower unit with the outdrive to the side of centerline, or tilted/trimmed above or below. If that CV joint went out you would not have a doubt as to a problem. When the joints start wearing you will start to pick up vibrations at the hard right-left steering positions or high tilt with the engine running.

In F gear, the prop ratchets in one direction and is solid the other. The ratcheting is in the cam follower in the lower unit and is there to allow the prop to freewheel upon deceleration where the engine rpm is lowered by you and the prop is turning faster than the engine...like when you come off plane. N you have and R locks in both directions. When going to R with the engine off, someone needs to be rotating the prop while you shift the linkage. If you don't get the cam follower pin aligned with the slots in the R gear, you can bend your shift linkage and doing what I said will prevent it. When the slots and pins line up the shifter will go all the way back and lock the prop to the engine.

Take another look and get back. Might disconnect the shift linkage at the engine and see if just moving the engine linkage will work for you. If so, then suspect your control box. They do fail and if your control is original, on an '87 boat, then suspect it...and you said that's all you did...throttled back to N, shut the engine off, cranked back up and SHIFTED into (supposedly) gear..Quicksilver 2000 or 3000?

Mark