Mercury 3.3 HP gear/propeller issue

slawosz

slawosz

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Hi,
out of the sudden and on the most unwelcome moment (boat tided up, etc), just before mooring, engine propeller stoped spinning. I checked now what happened - there is plastic part of propeller spinning around shaft. I guess it is shear pin blocking it from coming off? How to get it off the shaft?

Here is photo of plastic part - I managed to take out the propeller:

image uploader
 
I have the Mariner 3.3HP version and the prop. is simply held in place with a split pin. It slips into the groove shown in your picture and the entire prop. slides off after removing the split pin. My prop. doesn't leave a plastic insert behind. The shear pin passes through a hole in the driveshaft and fits inside recesses in the rear face of the propeller. My prop. was quite difficult to remove initially and I imagine the insert on your version could be pretty tight.

It looks as if your prop. has a soft insert with grooves and I imagine these replace the shear pin and allow the driveshaft to slow in a controlled fashion on impact. I haven't seen this version of the 3.3hp but imagine that the insert will slide out and to reveal a stronger "shear" pin inside. It might be quite stiff to remove but I can't see any reason for anything other than a friction fit.

If nobody else replies with more detailed information then i may be worth applying a little bit of force to see if it moves. I have just noticed the blurry prop. in your picture and it does have grooves, confirming that this is designed give better protection in event of an impact.
 
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slawosz said:
Hi,
out of the sudden and on the most unwelcome moment (boat tided up, etc), just before mooring, engine propeller stoped spinning. I checked now what happened - there is plastic part of propeller spinning around shaft. I guess it is shear pin blocking it from coming off? How to get it off the shaft?

Here is photo of plastic part - I managed to take out the propeller:

image uploader
Click to expand...

I would not have expected the prop itself to have separated from the plastic bit .. Once the split pin was removed the entire prop complete with hub should have pulled off the shaft.

If the plastic bit is rotating freely on the shaft the shear pin through the shaft at the back of it has failed.

Pull the plastic bit off....... Refit it into the prop. then refit the whole prop using a new shear pin. Finally refit the split pin

But check that the plastic bit and the prop itself are not damaged and that it will transmit the drive properly to the prop and has not "spun" ( it looks OK in the picture)

EDIT
grease the prop shaft with the recommended grease before refitting the prop
 
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Thank for answers. I just wonder how I can pull this plastic bit off the shaft? Do you think it is possible it somehow got stuck on shear pin somehow? I really had hard time trying to pull it, screwdriver lever does not really working - there is no much room and plastic is soft. Do you have any advices?
 
slawosz said:
Thank for answers. I just wonder how I can pull this plastic bit off the shaft? Do you think it is possible it somehow got stuck on shear pin somehow? I really had hard time trying to pull it, screwdriver lever does not really working - there is no much room and plastic is soft. Do you have any advices?
Click to expand...

Like Vic, I would have expected the rubber insert to be bonded to the prop bush. If that is the case, then I suspect that the prop is not going to be usable in future so you could just cut away the rubber insert. However, I would probably continue to try and prise it off unless someone comes on with specific experience of this prop. If you have removed the fixings from the end of the shaft, it must be removeable. Perhaps try putting large pliers/stillsons on it and twisting it back and forth a bit with the engine in gear.

EDIT No shear pin = no gear. Sorry. However, the twisting/shearing action from large pliers might well still be the answer even without a shear pin.

Richard
 
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slawosz said:
Thank for answers. I just wonder how I can pull this plastic bit off the shaft? Do you think it is possible it somehow got stuck on shear pin somehow? I really had hard time trying to pull it, screwdriver lever does not really working - there is no much room and plastic is soft. Do you have any advices?
Click to expand...

I still haven't found any reference to this style of propeller. The ones I've found all look like the propeller fitted to my 3.3hp outboard (https://www.amazon.co.uk/Propeller-309-64106-0-309641060M-Evinrude-outboard/dp/B018FZB06E). Pictures in the link don't show any insert, just a solid moulding with a recess for the shear pin.

I still think that it is simply seized on the shaft, my propeller was very difficult to remove for the first annual check. No problem in following years as I lubricate before assembling.

Diesel is normally a very good penetrating fluid but it sounds as if the part stuck to your driveshaft is a rubber/neoprene/plastic material. Diesel is very likely to soften it and also make it swell, not exactly what you require. Perhaps someone can suggest a better a penetrating fluid. You could also try gentle heating with a hairdrier or pouring hot water slowly over the fitting. It might loosen it a little and allow it to be levered out a bit. It should be fairly safe if done sensibly and the water will just evaporate eventually if it does not work. A drop or two of washing up liquid will help the water penetrate.

Have you located a replacement propeller? Perhaps the supplier can supply fitting instructions to help dismantle the existing propeller.
 
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There is plenty of replacement on ebay.
I used quite lot of force and thick screwdriver, and managed to remove remaining bit. Turned out, shear pin was made out of nail, both ends were flattened to the shaft and plastic bit ripped...
I wonder if I should repair it with JB Weld epoxy or buy new one. Split and shear pins are already ordered....

 
I ordered new for 20 quid. I will repair this one and keep as spare. I use this as primary engine for my Achilles 24 and I am not sure if I will have peace of mind with repaired propeller.
 
I buy 4mm brass rod from B&Q and cut it up. 1m makes a lot of shear pins.

I use my 3.5 tohatsu to push a 2.7m inflatable dinghy. The shear pin slot is damaged and I think I lined it with bent aluminium but I do wonder whether more pitch on the prop would be advantageous and the engine seems very lightly loaded.

Seeing the price of those props may make me investigate further.
 
slawosz said:
There is plenty of replacement on ebay.
I used quite lot of force and thick screwdriver, and managed to remove remaining bit. Turned out, shear pin was made out of nail, both ends were flattened to the shaft and plastic bit ripped...
I wonder if I should repair it with JB Weld epoxy or buy new one. Split and shear pins are already ordered....

Click to expand...

Making a bit more sense now, it looks as if the propeller is metal with a plastic insert. The ones I've seen have been all plastic where a single part makes more sense. I can see why a metal one would have the insert.

It might also be a possible explanation of the newer shear pins I bought. The original type were quite soft and needed to be replaced every 1-2 years because they had a distinct bend. The new ones look like pretty solid stainless pins and I can't see them bending. I was dubious that they'd shear but was told that they were original parts, perhaps they are intended for a metal propeller.

It looks as if your metal propeller has a toothed section engaging with slots on the insert. That would allow the drive to slip on impact, perhaps the pin is now more like a drive pin rather than a shear pin.

It would be useful to know if this guess is correct.
 
Hi
This is an after market prop. The hubs are sealed in and different to the genuine one.
I’m going to guess that someone has fitted something other than a shear pin for this to happen.
Replace it with a genuine one. They aren’t dear.
 
Propeller is plastic. Metal bit on the top left corner of the photo was used as shear pin. I don't think propeller could slip on insert. I got new shear split pin from ebay, looks solid, but as my propeller is protected by keel, I don't need to worry about it too much.
 
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