Replacing a Harley-Davidson Sportster oil tank (pre-2004)

The Sportster has been leaking oil from the oil tank for a while now, and after just putting up with it I decided to finally fix it.  I got a take off tank from eBay and sanded and painted it.  Yesterday I had some time to replace it so gathered everything up and went to work.

Bike with improvised sidebag

Hey, that's an empty garage!  "Millie's Garage" is full of all the stuff that used to be in this garage so I moved back over to the house we are about to sell instead of using my future bike shop that is one big storage unit right now.  But I didn't bring over either lift as getting them out would have taken longer than this project.



Battery and accessories removed

 I started by pulling the battery, which I've done a few times and gotten pretty good at.  This time I knew I was completely removing it, so I labeled the repositioned coil wires and pulled the chrome cover, coil and battery all as one piece.  Much easier than wedging it back together.  I also had to pull the repositioned ignition switch before removing the battery box.

There was oil everywhere, as expected since the leak was coming out of the top battery box-oil tank mount.

Sportster battery box and oil tank removed

 Here's what everything looked like once I got the battery box and the oil tank out.  See the wiring loom?  Lots of oil on it, and didn't feel like completely pulling the wiring harness off and cleaning it for hours.  Frame was coated in oil and grit, so that got cleaned up too.  And yes, there are more wires, switches and relays than I think are needed for a fairly basic bike.  Thanks DOT, EPA, and CARB!

Notice the rear mounting tab for the oil tank?  It's for a nylon nut that has less clearance to the rear fender than most tools will fit, and no way to turn an open end wrench more than a quarter turn.  I think this is the same for all the Evolution Sportster oil tanks through 2003, but I may be wrong as they changed oil tanks once or twice during the run.  A claw foot wrench might work, but I finally wedged a 7/16th socket in there with an extension and made it work.  Have fun when you do this project!

 Back together and home before the rain started.  Short ride but no big leaks (have blown an oil line right after an oil change before!) and a longer ride today with no leaks either.

Let's see if there is a puddle anymore.  Not yet.  Sweet.

All in all, a pretty straightforward project well within my confidence and skill level as an average mechanic.  Cleaning the bike took about 1/3 the time, so if I had caught this earlier it might have been quick, but still only  took about 3.5 hours.  Probably could do it in 2 to 2.5 hours next time.


I didn't post the pic, but the bottom mount had already been brazed on the oil tank at least once already.  Seems like leaking Sportster oil tanks are a common occurance, especially when fasteners have vibrated off.  As one shop advised me, might as well replace it and braze the old Sportster oil tank as a friend or I will need to do this again if we keep riding any real mileage on these bikes.

EDIT/UPDATE:  This is my most searched and viewed post!  If you find it helpful working on your oil tank, please comment and share any tips you learned.  Thank you-