RR blowing oil out breather after a run

[limeyrob]

OK my RR is leaking quite a bit of oil out the breather during and after a run.  Its not blowing a lot and there's decent compression. Also it doesn't wet sump or pump oil out the breather when cold.
It has an SRM pump, an ally sump plate and flat sump gauze and a full flow return filter.
My suspicion is that the flat gauze is not draining the sump quickly enough and the oil level is going up.  Since there's a full flow cartridge filter my next check is to take the flat gauze plate out.
The original gauze is a top hat with a lot more area and its a coarser gauze than the flat ones now available but mine was missing hence the modern replacement.
My other suspect is the cork washer on the timed breather. I set this this just touch, would a thicker cork make a difference?
All thoughts very welcome as this is causing me a lot of head scratching!

[DAVE BRADY]

Hi,

I have heard the idea about the gauze before and it is feasible so try that first as it is the easiest. However, the last A65s had a flat filter gauze so it should be OK. It is also possible for the return pipe to come out of the case allowing the oil level to rise before it is scavenged. Oil will then blow out of the breather.  This will be obvious when you remove the gauze.
The cork should be compressed by the 'top hat' to ensure a good seal.

Dave.

[limeyrob]

Thanks, hadn't thought of the pipe coming loose, I'll check. I think I'll pull the gauze out and see if it makes any difference. I recently heli-coiled the crankcase studs so I'm feeling confident....
What is the path for oil to the breather?  I'm thinking if the sump level is high its picking up on the flywheel and getting thrown in the cam trough.  From there its draining into the inner timing cover. But the breather pick up is quite high.

[DAVE BRADY]

Hi,

 As it is a timed breather it operates as the pistons descend so that there is no resistance and no pressure builds up in the crank case. I think it closes just as the pistons start to ascend so that nothing is sucked back in. When there is too much oil in the crank case the oil will be getting flung about and there will be more in the inner timing cover where the breather is. This oil will get pushed out of the breather regardless of how good the cork is. The cam through is not part of the breather as there is a separate drilling running parallel to the cam.  If you replace the cork then all will be clear as you will the 'top hat' and the drillings/vent holes.

Dave.

[limeyrob]

Thanks, yes I'd forgot the cross drilling.  Pulled the sump off and took the plate out. It could be the culprit, not sure until I do a run.  The gauze is a bit more dense (thicker wire) and the area is reduced by the crimping around the edge compared to some.  Also (my bad) I found some Hylomar on it blocking it a bit.  When you compare the flat plate I have to the original with the raised gauze the original has a lot more surface area, perhaps close on double.