Merc. 470 shifting problem

[ErieRon]

Gentlemen;

I have a 1984 Merc 470 S.N. 6701134 with an Alpha 1 drive.

Sterndrive S.N. 06753035

Outdrive S.N. OF161976

While on the water recently I started the engine and as I shifted to forward the boat began to move, but immediately stopped and a whining noise was heard. That shift felt normal, momentarily anyway, but the momentum stopped abruptly and the whining noise was heard. The noise seems to be coming from the transom assembly (general area anyway) as observed from inboard since we were on the water.

I shut it off immediately and checked the shift cables and they appeared to be working (moving anyway). I restarted it several times and it whined in idle. When I attempted to shift, it felt somewhat normal, but weak, tension-wise, and the whining increased as I attempted to shift.

There seemed to be light tension on the throttle the first couple of times but eventually the tension on the throttle was gone, and as I shifted it only seemed to be throttling up...then it would stall out. I couldn't even feel or hear it trying to engage the gears.

As it stands now, it is on my trailer and I am wondering where to start.

I have downloaded and read the manuals and procedures, but I am still pondering a starting point. The lower shift cable is an obvious potential cause, but I have not heard anyone mention the whining sound in this forum. I have also read up on the interrupt switch, but that seems to be related to shifting out of gear, as opposed to into gear.

Note: The outdirve is only 5 years old due to theft. The S.N above is from the original.

Any suggestions would be greatly appreciated.

Thank you in advance.

Ron

 

[Don S]

Re: Merc. 470 shifting problem

Start the engine back up and see if the shaft from the drive going into the coupler is turning, also look at the coupler where the shaft goes in and see if there is any metal shavings around it.
Sounds a lot like you lost the coupler splines.

 

[ErieRon]

Re: Merc. 470 shifting problem

Don,

Thanks for the quick reply. I'm assuming you are talking about the prop shaft and not the drive shaft. If so, is the coupler you refer to the same as the Pinion Nut Adapter?

Kind regards,

Ron

 

[ErieRon]

Re: Merc. 470 shifting problem

Don,

I did not start the boat and check the shaft from the drive as you suggested (Re. 08/02 post).

When I looked down at the shaft, I noticed that the O-ring closest to the engine end of the shaft is visible. It's about 1.0" (inboard) from the transom assembly and in plain view. Also, there is approximately 2-1/2" to 3" of spline visible on the engine side. I have never really studied this before and don't have a reference for the orientation, but the O-ring does not appear to be oriented correctly. It is in it's groove. Is it just used as a guide during installation, or is something wrong here?

Thanks in advance.

Ron