Hey everyone. I am a bit of a newb when it comes to maintaining my own bike and Harley's but for the most part, am confident in my mechanical abilities. I am getting confused on this one so I think it's best, if you are interested, to give you the full story.

I had a leaky oil hose (the one to drain the oil to be exact) that I changed out a couple of months ago. shortly thereafter I noticed that I had oil spewing down the right and some on the left side of my bike. I checked my oil and noticed it was high so I sucked some out with a turkey baster to a proper level. I let the bike warm up with the side covers and seat off, checked the oil, and let it idle to see if I could see any leaking oil. All 4 hoses looked good and I didn't see anything coming out of the oil tank itself. Test rode it for 20 minutes or so periodically stopping and checking for leaking oil and the level. All was good.

The next morning there was a small puddle underneath the bike by the rear master cylinder. I figured its just an oil puddle that found its way out while riding. A couple of days later I rode it around about 60 miles or so and everything seemed to be just dandy.

I didn't notice any leaking oil or anything until today when I got to work, oil had spewed down the right side and was dripping off the rear master cylinder. When I peered under the seat, near the relief valve, I could see a puddle. I checked the oil, that had been at a normal hot operating level, and it was now over full, again. While sitting there I did notice that the oil level was dropping inside the tank right in front of me (and no it wasn't coming out on the ground.)

Is this something related to, somehow, still having too much oil in it? Or is this something else that I am missing like a clogged oil line or...?

This has been going on for too long and I'm convinced it is something simple.
I need to be able to ride this thing. It is my sanctuary and for now I can only look at it.

For a little history on the bike, it has roughly 30,000 fun but well cared for miles on her. It's a 2011 Nightster and my only modification is a K&n air filter.

Thanks

 

Maybe by chance there is a slight crack in the oil tank dain tube nipple on the tank. I've read that they are prone to crack when too much pressure is applied to them.
Could be when hot the oil causes the crack to expand?????
Good luck.

You are checking the oil level with the bike warm, and standing straight up....correct?

 

Saw another thread where the oil tank had cracked at the seam. Just something else to check for.

 

i would agree that over tightening the hose clamp could make it leak but the leak is coming from under the seat/behind the left and right side covers not underneath the oil tank. Yes I am checking the oil with it hot and standing straight up. I Didn't think about the crack expanding once the tank gets hot from the oil. I don't know how the oil pumps work on bikes but on my Toyota when I am at higher rpms, my oil pressure increases. Is it the same on bikes?

I knew about the older sportster oil tanks leaking around their seams but did not know that the newer ones would. Mine looks like it is made of plastic. If that's the case does anyone know of a less expensive replacement than the stock one?

Im still confused on why the oil level when down inside the tank when I opened it to check it with the dipstick.

 

Yes, the oil pressure will increase with RPM's. That's why you don't want to have too low of an idle with the later engines lest you starve the top end for oil. People assume they're supposed to sound like the old Harleys that lope a bunch so they set the idle way too low. I do believe the older engines lope the way they do because of the valve overlap.

 

Sounds like wet sumping. The check-valve's ball bearing/seat in the oil line from the tank is bad, allowing oil to flow from the tank into the crank when you shut the bike down. If you shut the bike off and wait too long to check the level, it's draining down, resulting in an inaccurate oil level reading. Due to the inaccurate reading, the level is too high and oil is spewing out your air cleaner.
I'm guessing. Let us know what you find out.

 

Sounds like a logical possibility, great post!