So I have a 91 Fatboy with stock EVO. It was running fine for about a year after I got it. One day I pulled up to my garage and noticed a lot of primary fluid coming out the oil vent tube. I studied up and learned it must be crank seal. I replaced the seal and took the bike out for a test run. Immediately the vent tube starts shooting out primary fluid again. The engine oil level is fine as well as transmission oil. Primary fluid is low. I am thinking maybe the seal at the clutch pack.....any help is appreciated.

 

Are you sure the oil isn't coming from the transmission vent tube?

 

Post a pic of where the oil is coming out.

 

I am positive it is coming out of the Oil Pump Vent tube. I have even printed the oil pump schematics and compared it side by side. The transmission is at the correct level as is the engin oil. I am thinking I may need to either rebuild or replace the oil pump?

 

Since the primary oil can't get into the motor I don't see how you can have primary fluid coming out the breather tube.

 

I know that is what I thought. Turns out, the Primary can get into the Crankcase via the Crankshaft Seal, if the seal goes bad. I replaced the old seal which looked good and it is still doing it so I am thinking the oil pump is malfunctioning and sucking the primary fluid through some how.

 

1 The primary has no pressure in it.
2 The crankcase has more pressure than the primary so if there is a problem you will get motor oil in the primary not the other way around.

There is no way the oil pump can suck from the primary the oil pump is not your problem!!!

If you're bound and determined that the primary is leaking into the motor then you need to replace the seals between the primary and the motor.

 

The crankcase pulls quite a bit of vacuum as the pistons go up...transfer from the primary to the crankcase is well documented. If the crank seal is not the problem...there are two other culprits...the screws that hold the plastic clip for the stator wires, or the case is cracked in the seal area.

 

Well I decided to take her out today with an extension hose attached to my oil pump bent. I started her on the rack and monitored the hose and also had the primary derby cover off to watch the fluid. It sputtered a little but stopped. Runs fine now. Mystery of mysteries here.

 

The ones I've had experience with motor oil went into the primary.
I haven't had the primary oil go into the motor yet but if you say it can then I will take your word for it.