Questions re dis-assembling a propeller shaft coupling, and re Yanmar alarm

[Bajansailor]

We are trying to get the shaft coupling off the shaft on a Jeanneau SO 40 which is fitted with a Yanmar 4JH4E 54 hp engine and are a bit stumped.
I have been told that the shaft is a taper fit on to the coupling - but the end of the shaft is threaded, which suggests that the coupling might be screwed on to the shaft (?).
Copied below is a photo of the poor coupling.

We did try putting a socket spacer in between the end of the shaft and the forward coupling, and tightening up the bolts, but that had no effect. Hence why I am wondering if perhaps the coupling is screwed on?
If this is the case, do you literally just apply enough leverage (perhaps with the propeller?) anti-clockwise to un-screw it?

The reason for getting the shaft coupling off is because we want to replace the (rather knackered looking) shaft seal (which is quite probably 14 years old now, with 4,000+ hours of usage on it) with a new Volvo seal for a 30 mm diameter shaft.

Changing tack, a couple of days ago the alarm buzzer on the instrument panel decided to set itself off, while the engine was not running.
Is it likely that this is just a tempermental buzzer, or is the problem more likely to be at one of the sensors on the engine?

 

[michael_w]

Never seen a threaded coupling before, maybe LH thread? Any rollpins or keys to be seen?

The buzzer is probably a fault on the instrument panel. A friend's Yanmar wrecked its starter motor and ring gear when corrosion lead to the starter motor turning over whilst the engine was running. The starter motor caught fire which was a bit sporty at the time!

 

[Poignard]

I have been told that the shaft is a taper fit on to the coupling - but the end of the shaft is threaded, which suggests that the coupling might be screwed on to the shaft (?).

More likely the shaft is a taper fit with a threaded portion having a nut (and washer) to keep the male and female tapers tightly engaged.

There would be no sense in the end of the shaft screwing into the coupling because it would tend to undo when in reverse.

Can you disconnect the four bolts/nyloc nuts and then draw the shaft and coupling aft so that you can look inside the copling with a mirror to see if there is a nut in there?

 

[scottie]

Coupling on a production boat would not be threaded

Examine the surface of the body of the coupling for evidence of a pin which should be fitted amd may be filed clean and look on back edge for slot for key to shaft

Try the builder for information first.

Fitting the coupling solely by taper would be unusual but could work but unlikely most would have key and or locking pin

As suggested split the coupling and push the shaft back gently enough to use either mirror or mobile phone camera to see the end of the shaft

There seems very little room to push the coupling back without fouling the reinforcement under it from your photo


Cox engineering have good examples of stern gear set ups and worth checking

 

[Talulah]

Scroll down on this link.
http://jeanneau.proboards.com/thread/1477
It may help.
The above link comes from this site:
http://santosha.info/html/pss_shaft_seal.html

Were you able to seperate the coupling sufficiently to see if there was a central nut?

 

[pampas]

As said slide coupling back, check to see if nut fitted. If not, small piece of steel smaller than shaft size placed on shaft nip up with four bolts and this method requires longer bits as the coupling comes off, or if roon, looks as if there is, a three leggd puller.

 

[Spyro]

As the coupling isn't split and therefore cannot "clamp" onto the shaft there would be no way of ensuring the shaft didn't spin in the coupling so I would think it must be a keyed shaft with a nut on the end inside the coupling.

 

[prv]

Nothing to add on the coupling, but I know about the insides of the older Yanmar panels. There's a positive connection through the buzzer, then to the overheat and oil pressure light bulbs, then from each of those down to their respective sensors. When the sensor "goes off", it shorts its terminal to the engine block, thus completing the circuit to the negative side of the battery and activating the light and buzzer. A short to negative (including any metal part on the engine) anywhere downstream of the buzzer would activate it. Did one of the lights come on along with the buzzer? If not (and assuming the bulbs aren't blown) then it has to be a short inside the panel just after the buzzer. If a light did come on, then the short could be anywhere in the wire from that light down to the sensor.

Pete

 

[boaterbaz]

As other posters have said, the shft is probably tapered and a narrow nut with some kind od locking washer fitted into a recess. Before you remove the coupling half put a jubilee clip around the shaft to stop it sliding too far back. Very embarrising to watch the shaft disappear through the stern tube. It is suprising how much water comes through a 30mm hole!

 

[Marsupial]

Some of these couplings were shrunk on using liquid nitrogen (allegedly), no roll pins or nuts, not even a taper. I cut mine out with an angle grinder then for a laugh we put it in a 50 ton press - the thing still would n't move! Parting these things in situe is def a no no in some cases - others come adrift on their own and need roll pins and bolts to hold them together.

a split and keyed stainless coupling is the way to go - IMHO.

 

[FullCircle]

More likely the shaft is a taper fit with a threaded portion having a nut (and washer) to keep the male and female tapers tightly engaged.

There would be no sense in the end of the shaft screwing into the coupling because it would tend to undo when in reverse.

Can you disconnect the four bolts/nyloc nuts and then draw the shaft and coupling aft so that you can look inside the copling with a mirror to see if there is a nut in there?

This is the post that wins the prize.

Put old bolts into flange, and jam it with a crow bar to prevent rotation, then undo the nut in the centre. You will then need to tap it off.
Seasoned observers will note there is actually a slight amount of magnetic attraction in the shaft. Funny kinda stainless that Jenny use.

 

[Bajansailor]

Thank you all for the excellent suggestions above.

Tallulah's link to the Jeanneau Forum http://jeanneau.proboards.com/thread/1477 suggests that ours should have a key / keyway lurking within.

We had previously used a socket as a spacer, and then tightened up on the bolts in an effort to 'push' the shaft out of the coupling, but it wouldn't budge. Yet in the link above, they could just tap it off.......

Copied below are a couple of photos looking on the end of the shaft - unfortunately there is a nut in the way, obscuring any possible view of a key.....

For a scale reference, the string in the first photo is the strap on my camera, and is 4 mm diameter.

I'm sorry that they are a bit blurry.

Backtracking a bit, a mechanic had originally been engaged to do this work - he disconnected the coupling, unscrewed the nut from the end of the shaft, and then lost interest / absconded.
I found a likely looking nut with the bolts today, and thought I would see if it fitted. But no, it is too big, and it slipped out of my finger tips and is hanging on the threaded end of the shaft now as shown. The views are looking downhill, so it is difficult to persuade it to come back up hill. Think I will try tweezers tomorrow, or perhaps super-glue on two finger tips to hoik it out with.

I think we shall have to try using a spacer with bolts again as a 'pusher' - ideally a solid lump of metal rather than a socket, as the socket wasn't sitting very well the last time.
And try to find the proper nut......

 

[Talulah]

If I was doing this the steps would be:
1. Remove nut.
2. Attach bolts and insert spacer between shaft and gearbox.
3. Tighten bolts as tight as you dare.
4. Heat coupling with a blowlamp.
5. Sharp taps with hammer on coupling.
Repeat steps 3 to 5 as often as needed.

For handy spacer I would be using a socket with small extension piece.

 

[Talulah]

Incidentally, I have on occasions tried a different approach:
I've used a small car bottle jack as a spacer and then used that to open up the gap pushing the prop shaft away whilst the bolts retained the coupling. However, I found this didn't work as the bottle jack wouldn't work in a horizontal position, only in a vertical position. So I replaced the hydraulic jack with a regular car jack and that worked fine.

I had enough room to get a jack in because there was a flexible drive shaft that was removed first. (Aquadrive unit.)

 

[vyv_cox]

Seasoned observers will note there is actually a slight amount of magnetic attraction in the shaft. Funny kinda stainless that Jenny use.

Or in some cases, a lot of magnetic attraction and pretty poor corrosion resistance. http://coxengineering.sharepoint.com/Pages/Crevice.aspx

It is fairly clear that Jeanneau have made savings throughout their boats by selecting cheap metallurgy. http://coxengineering.sharepoint.com/Pages/Corrosion.aspx.

Seacocks are yet another example.

 

[chimere382]

thanks for info prv - the light came on for the oil pressure but now when the batteries are switched back on there are no lights coming on? So is it possibly both of your solutions - what do you think?

 

[chimere382]

I love the idea of the blowlamp - will try this savvo!

 

[tribblehunter]

Blowlamp in confined space???

Better have plenty of ventilation. .......And fire extinguishers....... Did this once as an apprentice. Blowtorch went faulty..... no eyebrows for a month.....

I would first try the spacer and coupling bolts, and if it does not come off pour a kettle full of boiling water over it. Then resort to an open flame..........

 

[Bajansailor]

It has taken a while to get the shaft coupling off, and here is a little update.

We took heed of suggestions above, and engaged a friend who happens to have access to an oxy-acetylene torch in the haul out yard. We used a socket spacer again with some extra packing washers to make up the required depth, but with 4 bolts this time on the coupling faces (previously we tried with only two).
Tightened up the four bolts in turn until they were all very tight, but nothing wanted to budge.
Applied the flame of the gas torch on a narrow section of the coupling and introduced some serious heat to it, and then tried tightening the bolts some more.
Still nothing.
Tried heat again, and then some more welly on bolts, and finally it started to shift.
The key is rather worn in cross-section especially in way of where it just protrudes above the level of the shaft - there seems to be a 'waist' here, so we shall try to replace it.
Am a bit baffled by the type of threaded end that is commonly used on the ends of these 30 mm diameter shafts for Jeanneaus.
I have tried various nuts, including fine and coarse 1/2", fine and coarse 14 mm, and (as shown in the photo below) a coarse thread 9/16".

Although this 9/16" nut has 'gone on' to pretty much the full depth of the nut, it did so very reluctantly, and with a liberal application of some grease (it is not S/S, but I didn't want to take any chances with stuff like galling).
I had previously tried a coarse thread 14 mm nut, and it didn't want to know, but I am thinking that maybe this was because the end of the shaft was rather burred from the effect of the spacer being pressed against it.
I had swopped it in the bolt shop for the 9/16", so I shall go back and get another 14 mm nut, as it seems more logical for a Jeanneau to have a metric thread rather than imperial (?).
If the 14 mm doesn't work, then I am thinking that the 9/16" will just have to do, as it can be wound on to almost the full depth.

The old Volvo shaft seal came off ok, and was found to be rather worn (as we expected). We have a new one to put on.
However as can be seen in the photo, the shaft is pressing against the top of the tube that the shaft seal goes over.
The reason for this is that the P bracket is not in proper alignment - it really needs to come back a bit, so that the cutless bearing and the bearing in the Volvo seal are in alignment.
However the P bracket is VERY solidly fibreglassed in, and it doesnt appear to have moved at all in it's lifetime, hence I am wondering if it was built like this originally.
If so, the cutless bearing has probably been replaced a few times by now.
I tentatively tried to start chiselling away the fibreglass overlaminations, with the intention of re-aligning it, but quickly went off that idea when I saw how long this would take.
The vessel has been with her current owner for 5 years now, and everything was fine when she was acquired, and the engine has done probably 200 hours of actual motoring since then (not counting battery charging, before a large solar panel was installed).
I would prefer to have the shaft in good alignment with the Volvo seal, at the expense of mis-alignment with the cutless bearing rather than the other way around, as it is easier to replace cutless bearings than Volvo seals.
Of course it would be nice if the cutless bearing was in alignment with the Volvo seal, but it isn't, and it would be a big job to make it so.

 

[fisherman]

Obviously you are on the hard, this may account for misalignment. When the P bracket was fitted the boat may have been cradled differently.