BMC 1500 diesel blowing oil out of the crankcase breather

[rob.s.uk]

I have a bmc 1500 diesel in my fishing boat. After a run there is about 500ml of oil that has been blown out of the crankcase breather. I have a bottle to catch the oil so I can pour it back into the engine. If it's a calm day there isn't that much but the rougher it is the more comes out as the boat rolls. Could it be the sump being pressurized by worn piston rings?. The engine runs lovely so it's not a massive problem but I would rather the oil stay in the engine.

 

[alldodge]

I have a bmc 1500 diesel in my fishing boat. After a run there is about 500ml of oil that has been blown out of the crankcase breather. I have a bottle to catch the oil so I can pour it back into the engine. If it's a calm day there isn't that much but the rougher it is the more comes out as the boat rolls. Could it be the sump being pressurized by worn piston rings?. The engine runs lovely so it's not a massive problem but I would rather the oil stay in the engine.

How long has it been doing it?
How many hours are on the motor?
Has the motor had regular maintenance as oil and filter changes?

 

[rob.s.uk]

I bought the engine about 2 year ago and fitted it in the boat. This is the first season I've really used the boat properly. As last year was mainly a testing year to iron out any problems as I rebuilt the boat as it was a large project. I don't know how many hours the engine has done as I have no history on it. I would imagine it's done hundreds of hours in its life. I don't know the service history but I think it's been well maintained as it runs without fault and I've never had a problem with it. Before I fitted it in the boat I gave it a good going over. Seals gaskets glow plugs oil filters waterpump fuel pump ect. It's only been blowing oil out recently but as I said I've only really given it a good run this year.

 

[alldodge]

Well reading up on the motor, many have had the blowing oil out as it ages. If you remove the breather cap and place a rag over it, the rag should stay in place. If it gets blown off the you have some major blow-by. The engine even with blow-by will last a long time. Also check engine oil level (mentioned if it rolls more then more oil come out).

As before might just deal with it, but 500 ml is quite a bit for one day running

 

[rob.s.uk]

I did suspect the rings. I just thought I would ask just in case there was a common problem with these engines. As you said they last a long time anyway. I may replace the rings over winter. I want to look after the old girl.

 

[alldodge]

Love a good diesel, most can be counted on for many years of operation. If you get into it I hope you could post your progress. Would be nice to see what she looks like

 

[rob.s.uk]

Will do

 

[pro-crastinator]

This problem also manifests itself if incorrect weight oil is used.
be sure its a 15-40 or such.

 

[rob.s.uk]

Thanks for the info. It's due an oil change so I will try the recommended oil weight you have said. Cheers rob.