Mercury 50 hp, no power at prop, engine runs fine.

[dennycook]

I'm trying to help a neighbor on a remote island with no boat mechanics. He hit a rock with his 2001 pontoon boat with Mercury 50 hp, and the boat ran for a few more outings however now the prop quit spinning when engine is in gear, it revs up but no go. He is convinced it is a shear pin but after pulling it out of the water to take a look I'm not so sure. I watched a couple of you-tube videos on removing the lower unit and one of them showed how the shift shaft rod moved up when in forward drive, in the middle when in neutral, and down in reverse...... his shaft remains stationary no matter what position the shifter it is in. I don't mind helping pull the lower unit off put I'm wondering if it could be a shift shaft problem that doesn't require the lower to be removed. I can not find any info on it, but if that rod isn't moving up & down could that be the problem and what solution can I search for?

Thanks,
Beav

 

[jimmbo]

A Merc doesn't have a Shear Pin to shear, as it has a Splined Propshaft and Prop Hub. It might have a Prop that has a Sacrificial Hub, and it has shattered. Or it could have a Prop with a Sheared Rubber Hub. Take the Prop off and look

 

[dennycook]

A Merc doesn't have a Shear Pin to shear, as it has a Splined Propshaft and Prop Hub. It might have a Prop that has a Sacrificial Hub, and it has shattered. Or it could have a Prop with a Sheared Rubber Hub. Take the Prop off and look

Thank you and I will check the hub first thing but I am still concerned regarding the shift shaft (rod) not moving when changing from forward-neural-reverse. If indeed it should move up and down (even if the motor is not running) would it be an adjustment issue or is something broken?

 

[jimmbo]

Check the Prop Hub First.

 

[brodmann]

If you supply the model number of the motor, we can tell you more about the shifting mechanism. Not all motors have a shift shaft that moves up/down, many have a shift shaft that turns. If the shift shaft isn't going up/down, look for the connection from the cable hookup to see if something has come loose there. But the others are right, it's more obvious that the prop was damaged when it hit a rock.

 

[Texasmark]

Hitting a rock really has nothing to do with the shifting mechanism....if the prop is doing its job as the sacrificial element. As Jimmbo said, remove the prop and inspect the hub for signs of damage especially if it has a replaceable plastic hub like is popular these days. If you have an old design, pressed in rubber hub, they usually slip and reset themselves when striking an object.

Curious that you may have a linkage problem at the top of the shaft whereby the shift lever is moving but the shaft isn't and he used it several times after the incident meaning it still shifted, indicating no damage at the top of the shifting mechanism.

The fact that he used it a few more times helps to point to prop initial damage that wasn't 100% and after subsequent stress finally broke free.....smells of a plastic replaceable hub in the prop.

 

[dennycook]

The prop and hub look fine.
Model #50ELPTO, 2001.

 

[jimmbo]

The prop and hub look fine.
Model #50ELPTO, 2001.

Still need the Serial #

As for the Prop and Hub looking Fine.... Is it a Rubber Hub Prop, or is it one of the Insert Hubs?

 

[dennycook]

Still need the Serial #

OT375948

 

[flyingscott]

Broken drive shaft.

 

[jimmbo]

If the shaft isn't moving up/down, is the linkage between it and the Shift Cable moving, when the Control is shifted from Neutral to Forward or Reverse? Is the Cable moving?

 

[dennycook]

Yes sir, the linkage is moving.

 

[jimmbo]

. I watched a couple of you-tube videos on removing the lower unit and one of them showed how the shift shaft rod moved up when in forward drive, in the middle when in neutral, and down in reverse...... his shaft remains stationary no matter what position the shifter it is in.

The serial # wasn't valid on the Mercury Site.
If the Linkage is moving but the Shaft isn't going up and down, then it sounds like the Linkage is damaged/disconnected

 

[dennycook]

The serial # wasn't valid on the Mercury Site.
If the Linkage is moving but the Shaft isn't going up and down, then it sounds like the Linkage is damaged/disconnected

Maybe it is - 0T375948 with a zero and not OT375948.
Would it be disconnected at the top or the lower unit, and could hitting a rock jar it lose?
And thank you helping us out!

 

[dennycook]

Let me add, according to this you tube video (link below) at the 45 second mark he shows the shift rod in F-N-R but this motor seems to be stuck in the neutral position as the jam-nut it just visible, so the prop turns freely. I tried to move the shaft/rod with pliers on the nut and it didn't budge.

 

[jimmbo]

Maybe it is - 0T375948 with a zero and not OT375948.
Would it be disconnected at the top or the lower unit, and could hitting a rock jar it lose?
And thank you helping us out!

The shift shaft looks like it is One Piece, if it not moving at the Top, then there would have to be an issue between it and the Shift Cable

 

[dennycook]

I am going to throw in the towel on this project as I think I'm getting in way over my pay grade. I do appreciate all of the replies and help offered, but at this point I'll suggest to the neighbor that he put the whole pontoon/motor on the ferry boat and send it over to the mainland for repair.

 

[jimmbo]

Impacts with Rocks usually don't damage the Shift Linkage, there might be a bit more to the Story that hasn't been disclosed. You might be wise step away