Bravo 3 with small leak from prop shaft

kennymaclean

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Mar 26, 2022
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when getting my bravo3/yanmar4lha setup ready for launch this week i noticed a sm all pool of oil below the props. it looks like a leak on one of the seals..... The oild when drained was completely black, no cloudiness at all.... my question is : will this small leak be ok to run ( it looks like no water has got in ) or is it too much of a risk? i think the drive was rebuilt about 3 years ago?
 

alldodge

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Any kind of a leak is not good. The leak may stop, but may not. If oil leaks out when cool, it may suck in water once warmed up and cooled back down

Had a brand new B3 drive and it started to leak so had it fixed. If its a very small leak it may be just fine, but the drive cost quite a bit

If it has Merc HP lube and leaks I would suggest getting it fixed. If it has another kind of lube, maybe synthetic, maybe not but still would wonder
 

QBhoy

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Could this have came from the exhaust ? Being a diesel an all. Black oil from the gearbox would be unusual.
 

QBhoy

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Think I miss read. So the oil drained out the gearbox was black ?
 

kennymaclean

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Think I miss read. So the oil drained out the gearbox was black ?
Yes. There was a tiny leak from between the propellor and the lower casing…. You can’t see it drip… just over time it gets wet…. When I drained the oil from the system to change it yes it was totally black. I’ve never done this before so unsure what is ok . Particularly the leak… leave it or pull the shaft and do the seals… do I pull the lower half and do all the seals ?
 

kennymaclean

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Yes. There was a tiny leak from between the propellor and the lower casing…. You can’t see it drip… just over time it gets wet…. When I drained the oil from the system to change it yes it was totally black. I’ve never done this before so unsure what is ok . Particularly the leak… leave it or pull the shaft and do the seals… do I pull the lower half and do all the seals ?
I’ll take a picture of oil and post later… it had a feint trace of grey/silver forming also as it poured into tray… like a slick.
 

tpenfield

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Take the propellers off for a better look. Next step would be to drain the outdrive, do a pressure test to verify the leaky seal.

Replace the seals as needed. Nothing good can happen by running the boat as is.
 

alldodge

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If it started off Green and is now Black, its getting really hot. Need to look further, bearings might be to tight
 

kennymaclean

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If it started off Green and is now Black, its getting really hot. Need to look further, bearings might be to tight
yes it is very different in colour....im waiting to hear from owner when this was last changed, and the extent of the refurb/rebuild last time.if i take out the bearing holder i guess i wont need to pull the full shaft ?...
 

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kennymaclean

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yes it is very different in colour....im waiting to hear from owner when this was last changed, and the extent of the refurb/rebuild last time.if i take out the bearing holder i guess i wont need to pull the full shaft ?...
the shaft has almost no play at all... i can flex it and see a slight movement on the seal, i t looks ok. does anyone have any experience of a better seal for this? i read somewhere thta there was a double seal to replace the single ?? i should have said the inside shaft seal was perfect, the outside was very wet.
 

alldodge

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You can remove the carrier bearing and have access to the outer shaft seal(s). The carrier holds the outer shaft seal. The new seals change from 2 individual to 2 seals in one, and do work better. The new seals will install in older housings

1 each Small inner seal 26-8M0033407 (replaces 2 each lip seals)
1 each Large outer seal 26-861694 (replaces 2 each lip seals)
Dimensions 3 - 3/8 OD, 2 - 1/2 ID, 13/16 wide
 

achris

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If the gear oil is jet black, then it's burnt. And it's getting burnt because the drive is overloaded. The props are far too big for that engine. Get smaller props so the engine can rev to the top end of the recommended rev range.

As for the leak, that could be a result of the oil being overheated (which overheats the seals too). You need to pull the drive and pressure test it. If it were mine, I'd be doing a full reseal. If one seal is burnt, they're all burnt.

Chris....
 
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