Losing oil from the oil tank fill hole

Energy One

BiggJimm

Member
2003 mastiff has been sitting a couple years. Checked my fluids and installed a new battery and new gas.. Fired right up and then I noticed oil coming from the air cleaner. Lost about a quart. Gained access the the oil pump check ball and gave it a lite tap to seat it. Ball looked good. Tank was close to empty so I added a half quart. Started the bike a let it run until oil erupted from the tank fill hole? Siphoned some out and restarted it. Watched the tank level rise then shut it off. What gives?
 

Jersey Big Mike

100K mile club
You are suppose to check oil level with bike HOT not cold.
If the bike has not been run in a while it will drain down to the sump.
If it was coming out the head and or the fill spout, you likely over filled it.
Personally I'd start the bike run it for 5 minutes and do an oil change
Afterwards run the bike for 5 minutes and check the oil level.
Also if its sat that long -- change the filter.
 

Big dog papa

Active Member
Troop Supporter
Supporting Member
Is it still coming out of the air cleaner or has that problem stopped?? My 03 chopper will leak out my breather if it sits all winter. But will quit after I shut it down then start it back up. I don't let it sit anymore.
 

BigDogRick

Well-Known Member
2003 bikes had 107c.I. S &S "evo style engines". They wet sump. When they sit, oil is wicked up the breather tube to your air cleaner. This same action occurs while the bike is running in very minor quantities. It is the nature of the beast. Evo style engines are Harley Davidson engineering- based engine platforms that rely on a sump action to circulate oil. Very reliable and durable albeit a little messy. I have had droplets of oil wick up into my breather for 21 years on my 2000 Vintage. It is no big deal. it is CRITICAL that you do not over-fill your oil reservoir. By over-fill, I mean (believe it or not) manufacture's recommendation. Do not fill your oil above the weld point of the filler tube where it meets your reservoir wall And you will be fine. Over-fill it and your engine will naturally evacuate the oil it does not need through your breather all over the right side of your bike at high rpm. if filled correctly it's a few droplets every hundred miles or so. if the bike sits long enough with ideal vacuum it will wet sump all over your garage floor! It's not magic. It's the same principle as sucking gas out of a tank with a tube after a mouth full of gas!
 

BigDogRick

Well-Known Member
Just in case I misunderstood which typical issue you are having, there is also the potential that, under pressure, oil forces it's way up the fill tube and past the rubber seal of your oil cap. That just means your cap has an old rubber seal and you need a new oil filler cap. You need to replace the cap not only 5o stop that from happening but also 5o make sure you s5ill have a cap at the end of your next ride. The back pressure that occurs when you start your bike will literally pop the cap off onto the ground if it does not have enough friction to resist the pressure. (I apologize for the random character mistakes - typos- I have an Apple iPad and the screen keyboard sucks. It seems that after a decade or so that cannot keep it from randomly selecting the alt character from a key - alas, apple needs some help from the old school evo engineers!)
 
Top