Can't refill outboard gearbox!

Discussion in 'Outboards' started by rosbullterrier, May 12, 2016.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    ??? Too clever for me !
     
  2. SamSam
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    SamSam Senior Member

    Well, I am pleasantly surprised! A snafu resolved and a primal oem one at that!

    If it's only a rubber gasket in the way, I would just drill it out. Since it's only the top hole, you only need a very small hole to let the air escape, nothing like you would want if you had to put lube oil through it.

    You might put a little air pressure into the case through the bottom hole so the drill shavings would be blown out when you drill.
     
  3. WestVanHan
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    WestVanHan Not a Senior Member

    Looking back on the manual on page 169,the upper plug is #4.
    On page 169 and going to page 168 it does look like a very tight fit in there.

    I'm glad to have helped out!
     
  4. whitepointer23

    whitepointer23 Previous Member

    Glad u found the problem but something is not right. Tohatsu would not have built it that way. It must have had the seal replaced before. Is it an old motor.
     
  5. rosbullterrier
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    rosbullterrier Junior Member

    Yes it is an older motor because pics of the later ones show the impeller/ water pump sited behind the prop instead of at the top of the gear housing (driven by drive shaft)

    The offending oil seal is not just a gasket, it is the metal holder with sprung wire inside the seal lips. the ball race is then tight up to it.
    It is so close that I could not blow through the top level hole.
    I suppose the side of the seal could be drilled - but design fault? - maybe the seal has been replaced by one with deeper sides?

    I only wanted to change the oil!!
     
  6. SamSam
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    SamSam Senior Member

    Oh c'mon, you want to take the whole thing apart. You know you do.

    You can turn it on it's side or upside down and put the oil in the bottom hole. The gearcase capacities were listed, I think it was 3 oz for your motor. As long as it gets in there, it doesn't matter how. I've never used the term before, but 'any port in a storm' seems applicable.
     
  7. rosbullterrier
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    rosbullterrier Junior Member

    - well I wanted to know what was wrong -
    but there are other things more interesting to take apart . . .

    no, it was just servicing through concern.

    Really
     
  8. SukiSolo
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    SukiSolo Senior Member

    Glad you got it apart OK. The later models have the impeller housing on top driven by the drive shaft. The older ones have the impeller on the prop shaft. The drawings are commensurate with my experience of these beasts.

    The top oil level plug should be adjacent to the impeller housing? Worth also checking the actual screw (top level) is correct ie length a if it is too long it may hit the housing. M6 pan slotted X 8 or 10mm? if I remember right. Even replacing an 8 with a 10 length might give you a problem, someone may have done this before. nothing should be touching at that point there should be clearance. If it is casting to impeller housing clearance that is the problem, just file it back a bit. If so it is a manufacture fault - rare, as these components are pressure die cast, unless there is a bit of flash that has not been trimmed off.

    Having just done 5 of this 'type', rebadged Tohatsus', (2.5 2 stroke, 3.3hp 2 stroke, 3.5hp 4 stroke), with likely identical boxes, not had any problem at all with refilling. All had the impeller changed, etc etc.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    The correct tool for this job is an axe !
     
  10. rosbullterrier
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    rosbullterrier Junior Member

    Stripped it down - I can confirm the drive shaft oil seal and ball race behind the top vent hole does completely prevent ventilation.

    Thus the top vent hole is inoperative and I shall pour the oil in down the forward/ neutral shaft hole before replacing the (top located) water pump housing!

    And I always thought my little Tohatsu was wonderful . . .
     
  11. SamSam
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    SamSam Senior Member

    If it's something that can't be fixed, maybe you could drill and tap for a vent hole in a location that will work.
     
  12. SukiSolo
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    SukiSolo Senior Member

    One note though, the drawings do NOT show a drive shaft oil seal as being outside the lower bearing. Unless of course someone has been playing around...
    The bearing should be seated in the housing but the top level gearbox screw should only be through the outer casing and not reach as far as the bearing housing.

    Please note Page 25 of the following Tohatsu Parts exploded drawings. Note this is for a 2009 engine model year with the impellor on top as you describe. I hope this matches your engine. The site contains drawings of all the earlier and later versions of this motor so get the serial number and check.

    www.tohatsuoutboardparts.com/Parts-Catalogs/Parts Catalog MFS2-2.5B-3.5B (2009) - (00221052-1).pdf
     

  13. latestarter
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    latestarter Senior Member

    The last thing you need is a tight fit.
    Unless air can escape as you put in the oil you will struggle.
    You could try using a cheap plastic syringe to transfer the oil.
     
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