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Old 20 September 2020, 14:43   #1
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4hp Tohatsu

Seen a “none runner” 4hp Tohatsu for sale locally, thinking of a project but would it be any use if I had to guess I would Say it was an ex aux/tender (More
Likely tender) motor for a yacht. What could i do with it assuming I bought it and got it working (details of fault very vague) and what sort of value does it have as generic parts?

What sort of cheap sib could it power and what sort of boat as an aux? 4m 5m 5.5/6m?
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Old 20 September 2020, 15:37   #2
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I've got a 3.5HP Tohatsu which is a good and reliable runner. I love it! I use it on a 2.5m rib (heavily loaded with 2 adults and not much room to spare) and it's fine to bay-hop even in a reasonably strong Spring tide on the Solent (north-east coast of Isle of Wight), but I'd suggest it might struggle with anything more than 4m (and even then not fast!).
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Old 20 September 2020, 16:54   #3
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Is it one of the Tohatsu/Mariner/Mercury/Yamaha 2-stroke models like my old one below?

If so I reckon they're a bombproof motor, great simplicity and usually it's hard to make them not work.
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Old 20 September 2020, 17:07   #4
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Originally Posted by Fenlander View Post
Is it one of the Tohatsu/Mariner/Mercury/Yamaha 2-stroke models like my old one below?

If so I reckon they're a bombproof motor, great simplicity and usually it's hard to make them not work.
Yes it does look like that and and apparently itís locked up canít pull it over so either major issues run with no oil and seized or minor
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Old 20 September 2020, 17:16   #5
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Wonder if it has a no-start in gear interlock that's faulty?
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Old 20 September 2020, 17:48   #6
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Wonder if it has a no-start in gear interlock that's faulty?
That would be the dream.... or it is just stuck in gear? My luck a con rod snapped and turned around jamming the crank
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Old 21 September 2020, 01:12   #7
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Is it one of the Tohatsu/Mariner/Mercury/Yamaha 2-stroke models like my old one below?

If so I reckon they're a bombproof motor, great simplicity and usually it's hard to make them not work.
It won't be that model as that's a Yamaha painted for Mariner
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Old 21 September 2020, 04:57   #8
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Or, maybe, water in the gearbox has seized the bearings. I have a mariner 2hp right now that has that issue - motor is in excellent nick. Not stripped the box yet, so remains to be seen whether I can get away with replacing the bearings or whether it'll be replacement box.

Last motor I did was a 5hp Johnson/Suzuki of about 2000 vintage. In that case, with a shifting box it was trash so a used one off ebay is now on it.

Unfortunately, until you get a chance to have a look at it yourself, it's impossible to tell - the difference, IMVHO, between seized crank, pistons, or box is very subtle - just a little snifter of movement on the flywheel hints it's box not crank, for example.

If it's the crank that's seized, motor is trash. If piston rings have just stuck a little - you might be able to free them up. If gearbox is seized - then depends how much water got in there. Years ago, Seagull engines ran best with a nice milky mix of seawater and gear oil in the gearbox.
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Old 21 September 2020, 05:09   #9
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>>> won't be that model as that's a Yamaha painted for Mariner

Ahh OK thanks Davie... I'm guessing mine was the earlier Mariner 4 2-stroke but the later ones seem to fit that Tohatsu look??
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Old 22 September 2020, 13:59   #10
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Or, maybe, water in the gearbox has seized the bearings. I have a mariner 2hp right now that has that issue - motor is in excellent nick. Not stripped the box yet, so remains to be seen whether I can get away with replacing the bearings or whether it'll be replacement box.

Last motor I did was a 5hp Johnson/Suzuki of about 2000 vintage. In that case, with a shifting box it was trash so a used one off ebay is now on it.

Unfortunately, until you get a chance to have a look at it yourself, it's impossible to tell - the difference, IMVHO, between seized crank, pistons, or box is very subtle - just a little snifter of movement on the flywheel hints it's box not crank, for example.

If it's the crank that's seized, motor is trash. If piston rings have just stuck a little - you might be able to free them up. If gearbox is seized - then depends how much water got in there. Years ago, Seagull engines ran best with a nice milky mix of seawater and gear oil in the gearbox.


A bit of seawater saved you a fortune on easystart!!
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Old 22 September 2020, 14:11   #11
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Never needed easy start - damn thing always started first time.
However you did need a hazmat suit to run it.
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