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bent propshaft

peterdewolf

New member
I have a 3.5hp 2 stroke M3.5A forward gear only. Seems my propshaft is bent. Had it pulled part way up a bank while fishing and a powerboat went past me at speed, sending a wake about a foot high to the bank, lifting my boat up and dumping it and the propellor into the mud. It was buried about 4 inches into the mud.
I've disconnected the gear case from the driveshaft housing and can see that the propshaft gears are nested behind the driveshaft gears ( as you would expect ). The water pump case won't withdraw completely from the proshaft. Possibly this is where it's bent but I can't see a visible bend. can anyone tell me how to remove the propshaft with a view to getting a replacement.
Despite the outward appearance of the engine the gears look immaculate so I'd like to give it a few more years. It's a swine to start but will run all day.
So far
Hope you can help.
Peter
 
Well progress so far. I worked out how to remove the entire lower gearbox, the driveshaft and exhaust housing tap out from the engine. Surprised to see that the lower drive shaft is connected by a square tube? I still cannot work out how to separate the lower drive shaft from the propellor shaft. Any helpful hints ?
Peter
 
you might try going to http://www.tohatsuoutboardparts.com/ and go to the Parts Catalog section of their website. They have PDF copies of most of the Tohatsu models on their website (no charge). Look up your model and find the section you're dealing with. It might show how the thing is put together so you can figure out how to take it apart :) <edit> And keep in mind that the older manuals will show "Nissan" models but they're exactly the same as the Tohatsu model (ie: Nissan NS3.5A is the same as the Tohatsu M3.5A)
 
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Thanks, I've been there and they just sell propellors or prop shaft bearings, seals etc, no prop shafts and I have their parts PDF, the diagrams give no clue how to separate these parts. There is a knack somewhere in this thing and from experience it's probably simple, I've worked on cars before and motorbikes but don't want to blunder around in the dark with this engine if I can get good advice first.
 
The A (fwd) bevel gear is pressed onto the shaft. It's part number 309642100M PROPELLER SHAFT $81.48. The prop shaft housing comes out of the LU along with the water pump housing.
 
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Thanks for that, I have the prop shaft housing disconnected alright. The parts diagram is better than I thought, it takes a fair bit of magnification, the problem is that I can't withdraw the propshaft and its gear until I withdraw the lower drive shaft and its gear. Zooming in to the diagram the gear on the lower drive shaft is splined and is held in place by an 'e' ring. looks like what I need to do is reach into the housing with long nose pliers and push the 'e' ring off the end of the drive shaft and that'll allow me to withdraw it then remove the prop shaft.
The price you're quoting for that part is dollars so obviously it's in the US. I'm in Belfast, Ireland, by the time I get it from US the VAT and import duty will bring it up to about $120-00 plus $30-00 postage and packing, I'll try a couple of folks who might be able to straighten it for me or even try the breaker's yard :)
Thanks again
Peter
 
Well, it doesn't have an 'e' ring as per the diagram, it wouldn't drop out but once again a little gentle tapping with a nylon mallet and it did just that, as you said, happy days.
BTW, in all my years of cars and motorbikes I've been used to opening my choke to start an engine, according to my Tohatsu manual which I just got yesterday the instructions are to close the choke to start the engine!! never heard that in my life before ! Can anyone explain why.
Obviously it's why my trusty beat-up old engine has always been a swine to start, I've been opening my choke then closing it when it fires up.
 
Air and gasoline don't mix very consistently; It varies a lot depending on temperatures and air flow speeds. The warmer the air/fuel mix, and the higher the velocity, the better it stays mixed. Conversely, the colder and slower the flow, the more the fuel drops out of the mix. So when pull-starting a cold motor, you close the choke (in this case the shutter) to increase the richness of the fuel mix so that it reaches that magic mix ratio where it can ignite. That's also why you don't need as much (if any) choke when re-starting a hot motor.
 
Excellent answer.You learn something new every day, after 30 years 'messing about on the river' I learned how to start an outboard properly today, many thanks for taking the time.
 
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