crank case oil breather

[Don2003BD]

Originally the breather was into the carb air filter. I moved to a separate air filter mounted on the side of the engine. Worked for a few years and no problems. The buike is 10 years old and for the last few years it will push out about half cup of oil out the breather but only if the bike sits for over two weeks. If started every week no problem. More than two weeks and a lot oil is pumped out. After warming up it stops and no problem.

I've asked many shops and the answer I get is "this is normal". Didn't do it when it was new. Not normal to me ...

2003 S&S 107.

Any ideas ?

 

[RRRUFF]

Likely the check valve in the oil pump. These engines are dry sump which means the oil is pumped from the oil tank through the engine and back into the sump. It is common for oil to leak pass the check valve in the oil pump and back into the crankcase sump and takes a little while to pump back into the oil tank once the engine is started. So oil will be pushed up through the breather before the oil can be returned to the tank. You may also be starting to get some blow-by past the piston rings and causing more venting from the crankcase.

 

[Sven]

The scenario goes like this:

1. I have a new bike = All oil pump parts are tight and o-rings are new and supple. I ride it everyday. Even took the breather to point another direction so I couldn't see how much oil I was going to burn?

2. I have a bike that is pleasantly wearing out = I let it sit now. The o-ring is cracked, dry, no memory for expansion. I now have a leak thru this shaft. My oil pump gears and covers wear down with the shaft spinning or a gear spinning on the shaft. There now seems to be a way for the oil to travel out of: oil pump gear shafts and cracked o-rings, say? And because there is a gap to leak from, along with the cracked o-ring in the pump shaft area, a wobbly shaft at the end of a cover that has a worn sleeve, do you sort of see where oil can weep out: if left sitting?

3. I am a dry sump engine = If I had the oil in the crankcase, all the oil would do is fall down from the top end and crankshaft, be sucked up by the oil pump inside the engine case. A wet sump kind of engine, needs to evacuate the oil in the crankcase, return it to an outside oil recovery tank, acting as a larger engine case to hold that oil. And no, I do not pour oil out the breather thru blow by. My engine stops any blow by when the excess is scavenged, is caught up with the oil bleed down. Show me blow by being a constant oil chucker if it was. OP mentions nothing about blow by.

 

[Brew]

Many have installed a puke can, do a search and you will find pics of what other members have done...

 

[DynoDave]

Sumpin's Up Here

Commonly known as sumping.
The cases fill up with oil if you let them sit, then puke out on the garage floor when you start it up. They almost all do it if you let them sit long enough. Fix? Well, depending on how bad, just leave it alone, or you can put a new ball in the oil pump, beat on the ball with a hammer, match the ball to the pump body with valve grinding compound, put a new oil pump on, etc.

 

[Mr4500dodge]

Breather hose location

I too have a question on breather hose. I just swapped my hoses over for some stainless one's, and was wondering has anybody ever ran the breather hose up under the gas tank. Obviously I still need the black and white check valve, but do I need a filter on it too? My bike only has 3800 miles and I've never seen it drop any oil before out of the breather. Would this be ok, or should I stay with the pack and dump it towards the ground?

 

[Mr4500dodge]

Breather hose running under the gas tank.