Knocking prop shaft

[VO5]

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

Painful ? PAINFUL ?

You obviously don't know the meaning of the word.

Here you are, butting in negatively.

dur has a problem he cannot solve.

All of us here are trying our best to help him, in the tradition of Thomas Edison for example, who tried 16000 times with different metals and alloys to create a lightbulb, until finally he tried tungsten.

This quest is not unlike. If he hears a noise it must be caused by something not right.

You can scuttle off if you like.

The rest of us will remain to help him until his problem is solved.

 

[VO5]

Now here is another possibility that occurs to me....

Check the copper fuel feed pipe from the tank to the engine.

Check if it rattles owing to vibration when the engine is running at low revs and does it knock against anything ?

Just a thought...another one...

 

[macd]

dur has a problem he cannot solve.

I think you might need to brush up on your comprehension skills.

dur had a problem he could not solve: over two years ago. I daresay he's come up with a solution in the interim. (If so, it would have been thoughtful of him to have mentioned it). Since he's posted just once since 2014, I think the chances of your manifold insights offering him anything helpful are slim.

svTazling has a current problem. Please feel free to address it, and him, but I suggest that dur is best left out of it.

 

[VicS]

svTazling has a current problem. Please feel free to address it, and him, but I suggest that dur is best left out of it.

And the correct thing would have been to start a new thread of his own rather than resurrect and hijack a two year old one which should have been left to slumber in its original bed unless, of course, Dur wanted to post any feed back.
On more vigorously moderated forums the thread would have been locked very swiftly.

However sv Tazling is a new member, perhaps not familiar with the finer points of forum etiquette, so we will have to forgive him and hope he learns from his crimes

 

[macd]

And the correct thing would have been to start a new thread of his own...

That was then: yesterday. The correct thing now...surely the polite thing, since plenty of forum regulars have since engaged with svtazling's problem...would be to continue to do so.

 

[VicS]

That was then: yesterday. The correct thing now...surely the polite thing, since plenty of forum regulars have since engaged with svtazling's problem...would be to continue to do so.

Yes maybe but his one and only previous post , 6 months ago,seemed to revolve around valve clearances in his Beta 20. He never answered any of the questions put to him or responded in any way to any of the replies by other forumites. Now he turns up asking about what seems like tappet noise on a brand new Beta 25.

 

[RichardS]

Yes maybe but his one and only previous post , 6 months ago,seemed to revolve around valve clearances in his Beta 20. He never answered any of the questions put to him or responded in any way to any of the replies by other forumites. Now he turns up asking about what seems like tappet noise on a brand new Beta 25.

I said that I wouldn't post again on this thread ..... but all credit to VicS for his detective work.

This thread has a surreal Alice in Wonderland quality about it which is rather addictive but I am pleased that others like Macd and VicS appear to be getting the same guilty pleasure from it as me, otherwise I would think I was losing my marbles.

Richard

 

[macd]

Thanks, Vic. That puts a slightly different complexion on it. Maybe he's dur's alter ego?
(It was a Bukh DV20, btw, that he asked about and presumably got rid of, not that it's of any great import.)

 

[macd]

otherwise I would think I was losing my marbles.

You are Richard, in the nicest posible way. I can say this with confidence because...sod it, where did I put 'em...?

 

[VicS]

(It was a Bukh DV20, btw.)

they're all rebadged skodas or something though

 

[seadog30]

Hi

Have a look at the bolts connecting the R&D to the coupling. It looks as if the bolt head in line with the shaft in the photo might be very close to the gearbox end of the coupling. This might cause the joint to be solid at this point and induce vibration at certain revs and loads.

This was the cause of similar probs on my boat.

Good luck

 

[RichardS]

Anyone else fancy a crack at it?

Alice

 

[Jesgatt]

Hi, After about 15 days of maintenance, yesterday I had my boat back in water. During the maintenance I replaced the shaft seal, removed and serviced the folding prop, added a rope cutter, checked the cutlass bearing, replaced the shaft anodes, etc. The clearance from the rope cutter to the cutlass bearing housing is about 7mm. I noticed that during the forward propulsion, there is a clicking noise (heard to be coming from the prop area). This noise is only done when in gear and at a specific rpm (around 2400 rpm). If you go lower in rpm or higher, no sound is heard. Anyone encountered this issue before? Thanks.

 

[Tranona]

7mm is tight, should be minimum 10mm to allow movement forward when you go into gear. Which type of cutter do you have?

 

[Jesgatt]

7mm is tight, should be minimum 10mm to allow movement forward when you go into gear. Which type of cutter do you have?

This kind: Rope Cutter – Safe Sea Shop. it is impossible now to remove with removing the prop

 

[Jesgatt]

This kind: Rope Cutter – Safe Sea Shop. it is impossible now to remove with removing the prop

The strange thing is that when the engine is below 2400rpm, there is no sound at around 2400rpm, there is a clicking noise, above 2500rpm, there is no clicking noise.

 

[Tranona]

OK so no moving parts. Did they advise how clearance you need? Normally when shafts are made they leave 12-15mm clearance aft of the cutless to allow water to flow freely and for the movement of the shaft forwards, which is on many engines in the range of 3-6mm, but can obviously be more with super soft or worn mounts. Usually when a rope cutter is added the shaft has to be extended to create the space for it. Looks like that cutter is 12-15me used up most of the original clearance. It could well be the cutter hitting the bearing housing, although it would more likely be continuous once you got to the revs where the power is pushing further forwards.

 

[smithy]

As Seadog30 says check the clearance between the bolt head and gearbox flange. If this gap is too small as you put more power on it closes up and touches. To check put a thin piece of tape between the two and check it after running, if its worn through you've found the problem. I think the R&D couplings can distort slightly allowing this to happen or if you assemble incorrectly and have put a washer in the wrong place.

 

[Tranona]

As Seadog30 says check the clearance between the bolt head and gearbox flange. If this gap is too small as you put more power on it closes up and touches. To check put a thin piece of tape between the two and check it after running, if its worn through you've found the problem. I think the R&D couplings can distort slightly allowing this to happen or if you assemble incorrectly and have put a washer in the wrong place.

The original query was 7 years ago so guess it will be fixed by now.

One of the problems when a new poster opens up an old thread rather than starting a new one with their specific problem.

 

[Jesgatt]

OK so no moving parts. Did they advise how clearance you need? Normally when shafts are made they leave 12-15mm clearance aft of the cutless to allow water to flow freely and for the movement of the shaft forwards, which is on many engines in the range of 3-6mm, but can obviously be more with super soft or worn mounts. Usually when a rope cutter is added the shaft has to be extended to create the space for it. Looks like that cutter is 12-15me used up most of the original clearance. It could well be the cutter hitting the bearing housing, although it would more likely be continuous once you got to the revs where the power is pushing further forwards.

Thanks for your reply. I will be checking for any scratches/dents once the weather is better and I can dive under the boat. In the meantime, I will use lower speeds to avoid any further damages. I will keep you posted. Thanks