Grinding noise when in gear

[christopherb]

Update: I visited the boat today, managed to separate the prop shaft from the gearbox, put it in gear and - no grinding sound. So that eliminates the gearbox fears, I had to leave it partly disconnected as I couldn't get the shaft fully back into its socket. Wondering if anyone has suggestions on how to do this with the boat still in the water. I'm thinking clamp mole grip on the shaft behind the keyway and whack it with a big hammer! But maybe that's too crude.

 

[Plum]

Update: I visited the boat today, managed to separate the prop shaft from the gearbox, put it in gear and - no grinding sound. So that eliminates the gearbox fears, I had to leave it partly disconnected as I couldn't get the shaft fully back into its socket. Wondering if anyone has suggestions on how to do this with the boat still in the water. I'm thinking clamp mole grip on the shaft behind the keyway and whack it with a big hammer! But maybe that's too crude.

If the shaft will not pull forward to re-engage in the coupling maybe whatever was grinding/loose at the prop end moved when you slid the shaft backward and is now restricting its movement forward. If so, I would not start whacking it.

Also, is that stainless bolt in the coupling all that is holding the shaft in the coupling? From the gouge in the shaft looks as though at some point it was not doing its job. Recommend you investigate that too.

 

[christopherb]

If the shaft will not pull forward to re-engage in the coupling maybe whatever was grinding/loose at the prop end moved when you slid the shaft backward and is now restricting its movement forward. If so, I would not start whacking it.

Also, is that stainless bolt in the coupling all that is holding the shaft in the coupling? From the gouge in the shaft looks as though at some point it was not doing its job. Recommend you investigate that too.

In fact the apparent gouge in the shaft is just a grease line indicating the shaft's original position. I think the fact that I can't get it back in is due to lack of leverage rather than anything having shifted.

 

[Seastoke]

Are them your mole grip marks already.

 

[christopherb]

Are them your mole grip marks already.

No.

 

[Seastoke]

In fact the apparent gouge in the shaft is just a grease line indicating the shaft's original position. I think the fact that I can't get it back in is due to lack of leverage rather than anything having shifted.

If the grease line was the original position it would be strait. Me thinks

 

[Tranona]

Suspect the engine/box is now out of line with the shaft. The shaft will be a very close fit - was it difficult to get it out? In hindsight it would have been better to uncouple from the engine rather than pull thee shaft out. That type of coupling often need tapping or even pressing onto the shaft.

 

[christopherb]

Suspect the engine/box is now out of line with the shaft. The shaft will be a very close fit - was it difficult to get it out? In hindsight it would have been better to uncouple from the engine rather than pull thee shaft out. That type of coupling often need tapping or even pressing onto the shaft.

Actually it came out surprisingly easily. I did consider the option you suggest of removing the coupling but the hex bolts holding it on are really tight. So I opted for the apparently easier option. With hindsight, removing the coupling would have been wiser. Anyway I think with some taps from a big hammer it will find its way in. I say big hammer but that's only because there isn't enough space to wield a claw hammer, which was all I had with me. A good size lump hammer I'm sure will have enough kinetic energy to move the shaft even with a small backswing.

 

[christopherb]

If the grease line was the original position it would be strait. Me thinks

I think it was the original postion but can't be sure as I wrapped the shaft in insulating tape to avoid the key dropping into the bilge. It could be smeared or a long way off. I'll know for sure when I get it fully home!

 

[Seastoke]

Actually it came out surprisingly easily. I did consider the option you suggest of removing the coupling but the hex bolts holding it on are really tight. So I opted for the apparently easier option. With hindsight, removing the coupling would have been wiser. Anyway I think with some taps from a big hammer it will find its way in. I say big hammer but that's only because there isn't enough space to wield a claw hammer, which was all I had with me. A good size lump hammer I'm sure will have enough kinetic energy to move the shaft even with a small backswing.

You would be wise to buy a copper mallet, or use a lump of copper or alloy with lump hammer.

 

[christopherb]

Final update: I visited the boat today, loosened the gearbox flange, clamped a vice grip just behind the key and with just a few light taps on the end of the grip with a heavy hammer the shaft slid home. The grinding noise seems much better in forward, still quite bad astern. I think maybe the longitudinal movement of the prop shaft has dislodged some of the grit. Next lift-out I'll see to the cutless bearing, for that is certainly the culprit.

 

[michael_w]

Be ready to raid the piggy bank for a new shaft. It'll probably be badly scored by the cutless problem.