Knocking prop shaft

[dur]

I have a shiny new Beta 25 to replace the MD11C which I broke last year. Almost everything was new so new shaft and cutless bearing but using existing prop.

I have a knock at tick over when in gear which speeds up into one noise (or it smooths out and goes away) as the throttle is opened. In reverse it is slightly less pronounced but still there.
I have disconnected the shaft from the gearbox and then there is no noise when in gear. Turning the shaft by hand there are no hard spots but it can only be turned slowly of course. There is a click as the prop blades turn from the feathered position. I have checked that the prop is secure and that there is no movement in the bearing.

As far as I can tell the engine alignment is good - professionally installed etc. The engineer thinks there is no problem but with a relatively quiet engine it is a shame to have so much drive noise especially considering it cost half what I paid for the boat. I don't think we had the same noise with the old engine but the whole thing was rather noisier so can't be 100% sure.

How much noise should I expect from the shaft / prop at slow speed. I have yet to take the boat any distance as I am worried about damaging something but maybe I just need to "run it in".

Any thoughts welcomed!

 

[Spyro]

I have a shiny new Beta 25 to replace the MD11C which I broke last year. Almost everything was new so new shaft and cutless bearing but using existing prop.

I have a knock at tick over when in gear which speeds up into one noise (or it smooths out and goes away) as the throttle is opened. In reverse it is slightly less pronounced but still there.
I have disconnected the shaft from the gearbox and then there is no noise when in gear. Turning the shaft by hand there are no hard spots but it can only be turned slowly of course. There is a click as the prop blades turn from the feathered position. I have checked that the prop is secure and that there is no movement in the bearing.

As far as I can tell the engine alignment is good - professionally installed etc. The engineer thinks there is no problem but with a relatively quiet engine it is a shame to have so much drive noise especially considering it cost half what I paid for the boat. I don't think we had the same noise with the old engine but the whole thing was rather noisier so can't be 100% sure.

How much noise should I expect from the shaft / prop at slow speed. I have yet to take the boat any distance as I am worried about damaging something but maybe I just need to "run it in".

Any thoughts welcomed!

Engine may be aligned ok but the shaft may not be central in the shaft. I had the same problem a while back. The shaft used to hit the stern tube on start up and when motoring at an angle. Depending on what shaft seal you have you need to be able to slide the seal forward on the shaft and measure around the shaft where it enters the tube. This can't be done in the water.

 

[Tranona]

Probably the shaft touching the tube as the engine rocks at low speed if you do not have inboard bearing. Shaft should be centre's in the tube before alignment. A flexible coupling may help if you don't have one already.

 

[theoldsalt]

Yes the shaft must be centred in the stern tube when the engine is aligned otherwise the shaft may hit the stern tube when the engine moves on it's mounts.

However another source of knocking may be a loose shaft anode as I have discovered myself.

 

[dur]

Thanks for those suggestions - the seal is a traditional stuffing box with new packing and no shaft anode present at the moment. Its a bit of a puzzler!

 

[Spyro]

You should be able to feel the knocking on the stern tube if that is the problem. You need to get the boat out of the water undo the hose clips at the rear end of the stuffing box gator slide the whole lot forward and check the shaft is central in the tube. You could make some spacers to fit round the shaft then then align your engine, remove the spacers and refit the stuffing box.

 

[FWB]

My rope cutter makes a knocking noise. It was worse when the prop shaft was removed and replaced too far in. Backed off and noise reduced. Just a thought.

 

[dur]

The stuffing box is on the front of the shaft log so no exposed tube. I will check that the shaft is centred in the tube but it certainly looked like it as there is a circular flange which retains the packing and if it was much off it would show.
No cutter. It does have a bit more shaft exposed between the cutless bearing and the prop than it used to. I guess it used to be 3/4" and now it is maybe 1 1/4".

 

[oldharry]

I had a quick look at this with Dur when he first launched and noticed the noise. Its a wooden boat so the inboard bearing and gland housing are firmly attached to the hull in such a way that it is hard to see how the shaft could have gone out of alignment during the re-engining. I have had a misaligned shaft hitting the stern tube, and this noise doesnt sound like that. Best described as the knock of a damaged ball bearing. Its not very loud, but you can feel it in the timber of the boat. As Dur says, the engine is smooth when disconnected, so we have to assume it is in the sterngear somewhere, but neither we, nor the engineer who did the installation can fathom what is causing it. As Dur says, rotating the shaft by hand doesnt reveal any tight spots, so it is quite a mystery.

 

[Scarboroughsloop]

Was the alignement done in the water? Timber boats move when afloat so what is in alignement ashore may not be in the water.

 

[dur]

Was the alignement done in the water? Timber boats move when afloat so what is in alignement ashore may not be in the water.

It is true it was set up ashore. I think maybe I will take the R&D coupling off completely and then try and check the alignment as it makes it hard to see what is going on.

Edit... some pics fwiw

 

[svTazling]

Coming in late here as I Google industriously for clues as to the strange ticking/knocking sound made by my brand new Beta 25.

I can hear this sound all over the place, as it is being transmitted through the hull. It diminishes considerably when the gearbox is in neutral. It is most noticeable at idle or near-idle in gear -- tickety tickety tick, tickety tick, tickety tickety tick -- sounds like lifter noise. Sounds like an old VW van. At higher RPM it seems to disappear, or gets masked by general engine noise.

I have crawled all over the engine compartment trying to locate the source of the sound and it is very hard to find. It is not very deep in pitch, kind of a light clatter. At present it *seems* to be coming from the front of the engine, maybe more to the left than the right (as seen facing the serpentine belt, that is, facing aft). Injector pump? sloppy valves? Should I be worried? Listening to Youtube videos of Beta 25's being bench tested or run up after install, I think I hear a similar clattering sound at lower RPM but it is hard to say. I wish I could listen to another brand new one to see if they sound alike.

It could be transmission-related but as I say, it seems loudest and crispest right in front of the engine.

Should my Beta 25 go tickety-tickety at low RPM or is this a sign of some kind of trouble that I should be demanding to have fixed while the warranty lasts?

 

[RichardS]

Most obvious explanation is tappet/valve clearances. Manufacturers usually specify that they are checked and adjusted after 50 hours running (or similar) so perhaps your's just need doing. It's a simple job but you might need a new cover gasket if you ever need to do it yourself.

Richard

 

[VicS]

Coming in late here as I Google industriously for clues as to the strange ticking/knocking sound made by my brand new Beta 25.

I can hear this sound all over the place, as it is being transmitted through the hull. It diminishes considerably when the gearbox is in neutral. It is most noticeable at idle or near-idle in gear -- tickety tickety tick, tickety tick, tickety tickety tick -- sounds like lifter noise. Sounds like an old VW van. At higher RPM it seems to disappear, or gets masked by general engine noise.

I have crawled all over the engine compartment trying to locate the source of the sound and it is very hard to find. It is not very deep in pitch, kind of a light clatter. At present it *seems* to be coming from the front of the engine, maybe more to the left than the right (as seen facing the serpentine belt, that is, facing aft). Injector pump? sloppy valves? Should I be worried? Listening to Youtube videos of Beta 25's being bench tested or run up after install, I think I hear a similar clattering sound at lower RPM but it is hard to say. I wish I could listen to another brand new one to see if they sound alike.

It could be transmission-related but as I say, it seems loudest and crispest right in front of the engine.

Should my Beta 25 go tickety-tickety at low RPM or is this a sign of some kind of trouble that I should be demanding to have fixed while the warranty lasts?

It might be worth exploring with a listening stick , or an industrial stethoscope if you can borrow one, to try to pinpoint the source of the tickety-tickety before tearing anything down.

 

[bluerm166]

I had similar hard to find knocking noise at certain revs (when the engine displacement on its mounts was greatest) which proved eventually to be the flexible greasing tube slapping against the hull in sympathy.

 

[RichardS]

I had similar hard to find knocking noise at certain revs (when the engine displacement on its mounts was greatest) which proved eventually to be the flexible greasing tube slapping against the hull in sympathy.

It's very confusing but this is no longer a thread about knocking prop shafts but a thread about something much more like clicky tappets.

Presumably this is why one should never revive a dead thread.

Richard

 

[VO5]

I have a shiny new Beta 25 to replace the MD11C which I broke last year. Almost everything was new so new shaft and cutless bearing but using existing prop.

I have a knock at tick over when in gear which speeds up into one noise (or it smooths out and goes away) as the throttle is opened. In reverse it is slightly less pronounced but still there.
I have disconnected the shaft from the gearbox and then there is no noise when in gear. Turning the shaft by hand there are no hard spots but it can only be turned slowly of course. There is a click as the prop blades turn from the feathered position. I have checked that the prop is secure and that there is no movement in the bearing.

As far as I can tell the engine alignment is good - professionally installed etc. The engineer thinks there is no problem but with a relatively quiet engine it is a shame to have so much drive noise especially considering it cost half what I paid for the boat. I don't think we had the same noise with the old engine but the whole thing was rather noisier so can't be 100% sure.

How much noise should I expect from the shaft / prop at slow speed. I have yet to take the boat any distance as I am worried about damaging something but maybe I just need to "run it in".

Any thoughts welcomed!

Greaser unit not secure in its mountings and vibrating against bulkhead ?
Or the greaser pipe itself similar ?
Just a thought...

 

[RichardS]

Greaser unit not secure in its mountings and vibrating against bulkhead ?
Or the greaser pipe itself similar ?
Just a thought...

Although that is a long dead question. See post #16.

Richard

 

[bluerm166]

Although that is a long dead question. See post #16.

Richard

No it's not a long dead question.
It's just been asked and is still being investigated.
I referred to the noise arising from the slapping greaser line exactly because it created what you would have bet money was a serious mechanical issue but proved not to be,despite sounding like metal to metal.There are various other lines/cables/fixings that could chatter due to resonance,especially as the engine comes under load.

 

[RichardS]

No it's not a long dead question.
It's just been asked and is still being investigated.

This is getting painful so this will be my last post on this subject:

Please refer to VO5's post #17. The question VO5 is answering was posted by Dur on the 22nd April 2014.

I don't regard a question from over 2 years ago as having just been asked and still under investigation.

Richard