Leaking oil

[Ptol672018]

Hi, new to this forum and I wonder if anyone knows if it's possible that the oil pump is bad, the engine is a Yamaha 175hk 1986 model that has not been much driven with standing still for very long periods. The engine drains the oil through the carburettors when it is not running, what can it be? Can the oil reservoir on the engine be dense so that it gets over pressure or is it buying a new pump?

[walleye1]

Is the boat oil tank higher than the engine [like mounted in a pontoon boat]?

[walleye1]

If the oil tank is not being over filed, may be a check valve problem.

[99yam40]

old 86 model , makes me think check valves unless they have been replaced along with a new oil pump

[rodbolt17]

myself?
I would remove the check valves from the old kien pump.
then I would cut in 6 inline late style check valves.
then I would go play.
but that is just me.

[Ptol672018]

Thank you for all the tips, but if I understand you right, it's not a Mikuni pump orginal mounted but it's called Kien, but even if a new pump is expensive, maybe I'll invest in buying one with new hoses, what do you think? The pump is called 6G5-13200 something, but it is worth checking out what it's called.

Thank you in advance for your reply

[rodbolt17]

about 1990 Yamaha changed from a pump made by kien with internal check valves to a pump made by mikuni with external check valves.

[Ptol672018]

I only know that I want to trust the system so that the pump is holding. So you do not get all the oil that flows out of the carburettor. Is it difficult to mount a new Mikuni pump? Do you need a conversion rate?

[rodbolt17]

you buy the kit and a SM for your v6 only above a 1991 model.
actually all you need is the late style oil line routing diagram.

[boscoe99]

It is Keihin.

[boscoe99]

I only know that I want to trust the system so that the pump is holding. So you do not get all the oil that flows out of the carburettor. Is it difficult to mount a new Mikuni pump? Do you need a conversion rate?

What do you mean by "conversion rate"?

[boscoe99]

https://www.boats.net/product/yamaha/6G5-13200-00-00

[Ptol672018]

I meant that it would have to be rebuilt for a mikuni pump to fit.
Saw another post a week ago that had the same problem as me that oil is drained through the carburettors and what I understood then he would change the pump. According to the tips I have received on the forum, it has been talked about check valves, I do not really know how to do it, because it is unnecessary to replace the pump if not needed.
Rodbolt17 do you think it works if I replace only the check valves with the latest model?

[pstephens46]

I meant that it would have to be rebuilt for a mikuni pump to fit.
Saw another post a week ago that had the same problem as me that oil is drained through the carburettors and what I understood then he would change the pump. According to the tips I have received on the forum, it has been talked about check valves, I do not really know how to do it, because it is unnecessary to replace the pump if not needed.
Rodbolt17 do you think it works if I replace only the check valves with the latest model?

What would have to be rebuilt?

[99yam40]

I meant that it would have to be rebuilt for a mikuni pump to fit.
Saw another post a week ago that had the same problem as me that oil is drained through the carburettors and what I understood then he would change the pump. According to the tips I have received on the forum, it has been talked about check valves, I do not really know how to do it, because it is unnecessary to replace the pump if not needed.
Rodbolt17 do you think it works if I replace only the check valves with the latest model?

from what he wrote, all you have to do is remove the old check valves and install new ones in the oil lines. probably need to replace the oil lines and figure out the proper routing.
problem is how do you remove the old ones in the oil pump.

I would go with new oil pump and get everything new.
hope the kit comes with instructions on oil line routing