How to remove propellor shaft from coupling?

[Jokani]

I am trying to remove the propeller shaft so that I can replace the cutlass bearing and replace the stuffing box with a PSS seal.

After a struggle I removed the 4 bolts securing the coupling to the engine. But the coupling itself is now seized to the shaft.

I've given it a couple of gentle taps with a hammer with no success:

Any ideas how I can get the coupling off?

 

[Lon nan Gruagach]

Put a spacer (a nut) between the end of the shaft (only) and the shaft that sticks through the flange on the gearbox. If the bolts are long enough then use them or get some longer bolts to clamp it back together, pushing the shaft out of the flange.
An overnight soak in WD40 wouldnt go amis and you may need heat too.

 

[MoodySabre]

A good soak with something. But is that a taper which stops the shaft coming out of the coupling? You may meed to space the couple off the end of the gearbox with nuts. Then replace the prop nut and whack the shaft inwards to release the taper.

 

[Alpha22]

Go easy..... what would you rather replace, the shaft or the gear box? If you use the nut sandwich idea you can easily bugger up the flange on the gear box.

Cut the coupling off the shaft or cut the shaft.

 

[fisherman]

don't hit the end of the shaft, not good for gearbox thrust bearings. First establish what keeps the coupling on, is there a nut on the inside shaft end, is there a roll pin or similar through the coupling, are there grub screws. there will be something. Personally I would not baulk at lifting the engine if really stuck, not the end of the world, assuming you have access.

 

[PITCAIRN]

Dont know if you saw this video on You tube, showing the tried and tested method of using a socket placed between the end of the shaft, and the transmission, then re inserting the bolts and tightening up on the coupling fixing bolts - the socket acts to push out the shaft from the coupling (imagine taking a bottle of wine and putting the tip of your finger on the cork and pushing in on the cork as hard as possible, the cork will slowly push down through the neck of the bottle, your finger being the socket and the cork being the shaft) . See.... https://www.youtube.com/watch?v=qM45997JCRI

But also think, when the shaft and coupling were shiny and new, with no corrosion and crud holding the two together, what exactly was holding the two together ? keeping the shaft from just sliding out from the coupling - so I am thinking there is a grub screw hiding under that little dark brown 'circle' you can see on the body of the coupling. That will have to be drilled out probably.

 

[fisherman]

If there is a taper it will be smaller at the forward end, and there would be a nut.

 

[GrahamM376]

Looking at the photo, it appears there may be a pin which needs driving out. As others have said, put a spacer between the gearbox flange and the shaft then replace the bolts and tighten to drive the shaft out, don't hammer it. Some heat from a blowlamp and dousing in diesel or WD40 may help. If that fails, then it will have to be split lengthwise with a thin cutting disk, which shouldn't damage the shaft if careful.

 

[PuffTheMagicDragon]

There seems to be a taper pin holding the coupling to the shaft.

 

[Jokani]

Many thanks for all the advice, much appreciated.

I just found this on the Westerly Owners site:

"Remove the propeller and cutless bearing and unbolt the gearbox coupling. In addition to four bolts there may be a set screw through the side of the coupler".

Which confirms much of the above, but rather than a set screw, it looks like a taper pin (as PuffTheMagicDragon said), I remember seeing a smaller circle on the other side, I just didn't realise what I was looking at.

I guess if I am lucky, hitting the small end may release it. If not I'm not sure I would be confident trying to drill it out.

Are there any other options?

 

[ghostlymoron]

Looks like there is a key sticking out of the aft end of the coupling as well. Dousing with plus gas, applying heat and clonking with two opposing hammers may work. The key prevents the shaft turning in the coupling but there must be something resisting axial force as well such as a pin or grub screw. Mine's a split coupling so fairly easy to remove. (Not that I've tried it)

 

[Jokani]

Unsure what you mean by opposing hammers, I need to hit the pin with something like a punch?

 

[PuffTheMagicDragon]

Before you start hitting the thin end of the pin make sure that you pack the coupling from underneath (blocks of wood, etc) so that you do not bend the shaft.

Re the "opposing hammers": Hammer in each hand, hitting simultaneously on opposing sides of the coupling. In your case I doubt that you'll have much room to do this because the shaft seems to be in a 'trough'.

I had a similar problem on my coupling, very similar to yours, where I could not find any pin. It took me days of trying to figure out what to do. Eventually I poked a piece of wire into the thick grease that was in the bottom of the hole at the front of the coupling. Buried under the gunk was a large nylock nut on the end of the shaft!

If you try to push the shaft out of the coupling do NOT press against the gearbox (Volvo ?) because the casting is very thin and is very easy to crack - expensive! Use a 'strongback' with long bolts to two of the holes in the coupling's flange; place an old bolt, socket, or simlar between it and the end of the shaft and then gradually tighten the two long bolts a little at a time to 'jack' the coupling off of the shaft end.

Good luck!

 

[Jokani]

Would refitting the coupling with the 4 bolts provide enough support to hit the pin with a hammer?

 

[Spyro]

Have you checked there isn't a nut on the end of the shaft inside the coupling.

 

[fisherman]

Would refitting the coupling with the 4 bolts provide enough support to hit the pin with a hammer?

Would you put a shaft in a vice, slip a bearing on, then hit the bearing with a hammer? It depends on the robustness of the output shaft bearing in the gearbox and how hard you hit the pin.

 

[Jokani]

I'll get some degreaser and work away with some cotton buds to make sure it is a pin and not a nut, before I start swinging with a hammer.

I would prefer if it was a nut and bolt, seems far less risky!

I also have some Plusgas on order to try and reduce my pain.

 

[PuffTheMagicDragon]

Would refitting the coupling with the 4 bolts provide enough support to hit the pin with a hammer?

DON'T!

If I am identifying the gearbox correctly as a Volvo unit you would be risking serious damage. The 'bell' to which the coupling is bolted has an internal helical gear that provides the reduction. This engages with another helical gear that is on the drive shaft that comes from the engine to the box and is supported on roller bearings and these would be absorbing the blows that are applied with the hammer. Not a good idea IMHO.

Keep the coupling separated and pack solidly beneath it before letting fly with the hammer.

 

[Jokani]

That does look exactly like the gearbox fitted to my VP MD2B.

Thanks for you advice, sounds like you saved me some money there!

 

[fisherman]

Get a decent flat ended punch the right size to knock out the pin, if that's what it is. If it comes out you may still have a struggle, but the spacer/long bolts and push the shaft out should work, but worth remembering that this applies the same force trying to drag the coupling off the gearbox shaft. However, sometimes it's just easier and quicker to bite the bullet and cut the coupling using a 1mm disc in an angle grinder, first making sure a replacement is cheap and easy to obtain, and that you don't set fire to anything with the sparks.