Breather puffing oil out

[nevhunter]

Your return oil should have some air in it after a while. The scavenge pump is bigger than the supply one.to ensure the sump doesn't have oil retained in any real amount. If you have a lot of fumes you have blowby which is from the piston and perhaps the exhaust guide.. Nev

[Dick H]

My '49 NH does this and on investigating further I've found that nothing is going up to the rockers! Nothing at the oil gauge take off and nothing at the stud from the crankcase. (Both checked with engine running for several minutes). Obviously there's a blockage somewhere but how do I check and alleviate this? I'd be grateful for any suggestions.
Many thanks. Dick.

[jackcuddeford]

I replaced the pipe and tidying it all up and stopped a lot of the leaks, seems the main one now is from where the dyno going into the casing?
Think I might have a oiling problem...
Took the bike to a meet up tonight and was canning it down the motorway home. Think I got well over the recommended speed. Then the engine locked up. Luckily the clutch just slipped and I clutched and pulled up. Gave it 15 minutes and carried on...

[alan.moore]

There should be an oil seal that sits on the outside of the timing case where the magneto shaft (not dynamo which sits on top of the mag) goes into the case. Drags do a rubber one (original was felt). That seal may be missing or just old and not sealing.

Cheers
Alan

[alan.moore]

My '49 NH does this and on investigating further I've found that nothing is going up to the rockers! Nothing at the oil gauge take off and nothing at the stud from the crankcase. (Both checked with engine running for several minutes). Obviously there's a blockage somewhere but how do I check and alleviate this? I'd be grateful for any suggestions.
Many thanks. Dick.

Dick,
Are you getting a good flow back into the oil tank with the engine running?

[Dick H]

Thanks Alan. Yes, a very good flow. It was a bit bubbly but I put a recon. pump on that I had and now it's a nice even flow. It would seem that as nothing is going up to the rockers, oil is building up in the timing case and coming out of the breather. I'm more concerned about the lack of rocker lubrication than the oil leakage!.

[Bob.Murphy]

Yes, a very good flow. It was a bit bubbly but I put a recon. pump on that I had and now it's a nice even flow.

Bubbly is good ! It shows that the scavenge side is working and clearing the oil out of the sump. I would worry if the flow was always continuous as it would indicate that the scavenge side isn't keeping up with the oil feed.

Bob.

[david.anderson]

Dick
If you have no oil to the rockers it could be that the ball, spring and retaining plug in the timing chest is missing. The valve that I am referring to sits behind the oil pump in the delivery line to the bigend. That valve is normally closed so the oil pump initially directs oil up to the rockers. As the orifice into the rockers is small restricting the flow, oil pressure is created and with that pressure the valve behind the oil pump opens and oil is also fed to the bigend.
It could also be a blockage in the timing chest oilway or the oil line to the rockers as you have suggested.
I would not run the bike at all unless you have a good supply of oil to the rockers. Lack of oil to the rockers may result in the rocker arms seizing on the shafts, valves seizing in the guides, and reduced oiling to the cam and followers down the pushrod tubes will surely damage both.
David

[Dick H]

Many thanks Bob and David. I'll take all your points on board, and will certainly not run the engine until I've got this sorted, even if it means putting in another good engine I have (the bike's a hybrid anyway!). Best regards - Dick.

[nevhunter]

Just to sum up. Upon starting after a small time say 10 secs the oil should return to the tank in a steady stream initially, then become intermittent and in short spurts. That is NORMAL as the return pump has much more capacity than the delivery one.
Oil will not go to the rockers on the motors up to about mid 50 without some form of spring loaded valve between the pump and the quill going into the mainshaft on the timing side. Later models use a flow from the RETURN line to the tank so don't even have such valve. Your timing cover may be a later type and require modification by fitting the valve. That's pretty simple to do if you are careful and use the right bits. You don't need the spring to be too strong or worse coil bind which would block oil flow to the big end potentially completely..
Releasing one of the acorn nuts on the rocker box will confirm oil available to the rocker shafts. There could be a blockage but that's fairly unlikely in normal circumstances. It will more seep than spurt out. If you run or have run the motor without oil flow there's a big chance you will have the rocker shaft and rocker seize partially or eventually fully which may hold a valve open and cause it to get bent when the piston contacts it. It would be wise to dismantle the rockers and ease any marks or build ups on the shafts with a fine oilstone. IF it's in the rocker also, that makes it a bit more difficult. If you are lucky a very sharp round (rat tail) file may work easing any high spots, carefully.. Nev