Volvo D1-30 gearbox blowing oil out of breather

[Paulfireblade]

Bilge has always been clean until recently and traced source to gearbox breather.

VP gearbox model MS 10L-A is 11 years old and 925 hours on a D1-30f, reverse gear unit to a shaft driven prop.

Filler nut has a dip tube and breathes through a 1mm hole on one flat on bolt head.

Ran engine and gearbox for a few mins yesterday and sufficient oil to leave a smear of oil on casing around filler nut. Also on the passage I first noticed oil, I felt a very slight increase in vibration in the heads with the engine running.

Very little about the gearboxes on web.

Any ideas please?

Paul

 

[Beneteau381]

Bilge has always been clean until recently and traced source to gearbox breather.

VP gearbox model MS 10L-A is 11 years old and 925 hours on a D1-30f, reverse gear unit to a shaft driven prop.

Filler nut has a dip tube and breathes through a 1mm hole on one flat on bolt head.

Ran engine and gearbox for a few mins yesterday and sufficient oil to leave a smear of oil on casing around filler nut. Also on the passage I first noticed oil, I felt a very slight increase in vibration in the heads with the engine running.

Very little about the gearboxes on web.

Any ideas please?

Paul

Nothing really in there to pressurise it? Has it been over filled? Also check does your raw water pass through it like it does in my MS2? If so maybe a seawater leak is overfilling the box?

 

[Paulfireblade]

Nothing really in there to pressurise it? Has it been over filled? Also check does your raw water pass through it like it does in my MS2? If so maybe a seawater leak is overfilling the box?

Thank you, for the reply. No water cooling and oil level is correct

 

[Plum]

Bilge has always been clean until recently and traced source to gearbox breather.

VP gearbox model MS 10L-A is 11 years old and 925 hours on a D1-30f, reverse gear unit to a shaft driven prop.

Filler nut has a dip tube and breathes through a 1mm hole on one flat on bolt head.

Ran engine and gearbox for a few mins yesterday and sufficient oil to leave a smear of oil on casing around filler nut. Also on the passage I first noticed oil, I felt a very slight increase in vibration in the heads with the engine running.

Very little about the gearboxes on web.

Any ideas please?

Paul

Agree with what Beneteau381 said but to add.......... my VP gearbox, not the same model as yours, often has a film/smear of oil around the breather hole. When hot, expanding air will come out bringing a tiny amount of oil mist. Mine has been like this for the 10 years in my ownership.

 

[Paulfireblade]

Agree with what Beneteau381 said but to add.......... my VP gearbox, not the same model as yours, often has a film/smear of oil around the breather hole. When hot, expanding air will come out bringing a tiny amount of oil mist. Mine has been like this for the 10 years in my ownership.

Thank you, and your response gives me hope. Having said that, I had about an egg cup full of oil in bilge compared to normally clean bilge. I found the filler plug wouldn't tighten properly and on further investigation realised there was no washer.

I have now fitted a new filler plug/dip tube and washer (courtesy of VP only £140)

I might have to run it for a good deal longer to test properly, from what you are saying most of the oil comes out during warm up which is all I ran it for.