oil coming out of filler cap

[tilley12]

Hi,My Matchless G2 1960 has suddenly decided to blow oil out from the filler cap when engine is running.When I kill the engine the oil slowly drains back to the correct level.She starts ok and no excess smoke from exhaust.Could it be a blockage somewhere,would engine oil flushing help?Any suggestions would be appreciated to overcome this latest curve ball.

[Red Gauntlet]

A couple of things that could cause this, a blocked breather tube forward of the gearbox sprocket on the rear of the engine, or the breather tube may have come out of the timed breather stator causing it to rotate and shutting off crank case breathing. It maybe overfilled, try draining any excess oil from the crank case via the rear drain bolt, then restarting the engine.

[tilley12]

Ok thanks for the reply.Is this breather tube accessible or is it a case of just flushing it through or an engine strip down as there seems to be some muck in the oil filter when I cleaned it out.

[tilley12]

I have found the breather tube location on a parts diagram but still unsure of the timed breather stator you mentioned.Thanks for the pointers though.

[Red Gauntlet]

The stator is 042220 on the diagram and will be accessible once the engine is stripped down, muck in the oil filter does not sound good, maybe there are other blockages too if it has not been run a lot over the years, best way to check the breather is listen to it when you turn the engine over, it should hiss faintly. If the engine is miley then the end of the breather tube 042221 to stator join can wear badly shutting off the breather hole in the tube.

[tilley12]

Thanks very much for your advice and help.I will get my tools out and get started on it,although it's no 5 minute job.Cheers.