Another Suzuki 2.5 outboard issue!

[Misterbreeze]

I was running this outboard in the test tank today, all seemed well until it seemed to drop into gear on its own. Having stripped it down it seems the short prop shaft (normally engaged by the dog clutch) seized in the bush it runs in in the gear. So, 2 questions, why did it happen when there seemed to be plenty oil and can I get away with abrading the surface with grinding paste or is it a lathe job (friendly engineer neighbour) or new parts. I suppose if it seizes again at least it'll still have drive, be like having my old Seagull back!

 

[Ostara24]

When was it last run?
Last service?

 

[Misterbreeze]

This was the first outing since last season when it was flushed & stored. Although maybe 15 years old it's probably done less than 10 hours so there's every chance the oil was original. However it was clean with no sigh of emulsification.

 

[VicS]

Difficult to see how bad it is in the photo. You don't want to take off any metal so if not too bad I'd use some fine emery cloth and oil to smooth it up a bit. I'd probably mount it in the lathe as a convenient way of holding it.
Be sure to clean off any abrasive thoroughly before re-assembly

Why not take it to your engineer neighbour and ask his advice

(New prop shaft probably about £140. Gear and pinion about £180)


Were you revving it in neutral ? Not a good idea .

 

[Misterbreeze]

Revving in neutral - mea culpa. But in my defence I was following the manual instructions to determine that the cooling water flow was adequate ie rev up and down several times and watch for the result, which was fine. At the moment the shaft seized it had been ticking over gently for a minute or so.

 

[Ostara24]

Fast revving in neutral can cause of this, does the gear selector still work?

 

[Misterbreeze]

Hard to say as the seized shaft means it behaved as if it was permanently in gear. However the linkage at the top all looks good and no sign of damage at the lower end of the rod. Also I don't think there's any wear on either the little pin that actuates the clutch or the dog itself.

 

[Steve65]

Hi, had lots of experience with these clutch units. Usually they become damaged from engaging gear ehen the engine revs are too high. Only engage these at slow tick over.
Usually it puts a lip on the propshaft where the slot is.
Tap these down , dont grind them as you need the clutch dog slider with as less play as possible.

 

[Misterbreeze]

Just got the bits back from my neighbour - he's cleaned the shaft up on his lathe and polished it using grinding paste. Also, yes, there was a lip on the shaft which he also cleaned up but unfortunately this was done before I read your advice about tapping it down. In my non expert opinion the shaft still feels a little tight, although it loosened a bit once some oil was added but without knowing how it felt before the seizure it's hard to tell. I'll put it back together tomorrow and cross fingers.