Sportster Oil Leak

Around the 5,000 mile mark, I started to notice oil puddling on the engine block of my 2006 Sportster. The oil formation was on the right side of the engine, and my initial thoughts were that the oil leak on my Sportster was from a push rod tube seal. I wiped away the excess oil with the hopes of narrowing down the source of the Sportster oil leak. While the bike was under warranty, I need to have a better understanding of what the problem may be so that I could feel confident that the dealer was making the proper repair. Unfortunately, the engine need to be running for a while for the leak to appear, and the wind over the engine spread the oil around.

After spending some time searching the internet for clues about the leak, I found a few references to blow-by oil exiting the air inlet. Running my fingers along the inside of the air inlet, I felt a film of oil, and began to fear internal damage to the engine may have occurred. Time to call the dealer.

The service writer at the dealership shared that this wasn’t the first time he had seen this on 2006 Sportsters, but until the bike was looked at by a technician, it was hard to say the cause. When I talked to the lead technician, he said that they had seen some 2006 Sportsters where the piston ring gaps had lined up, causing the blow-by. While possible, this suggestion was still improbable, but I was assured that they would run a battery of tests to determine the cause.

Ultimately they told me that the air cleaner was saturated in oil and that the bike failed a leak down test. The Harley Davidson dealer tore down the engine looking for the cause of my oil leak. While the fault was not definitively placed on the ring gaps, they did re-ring my 883, and replaced the valve seals with a superseding part number. I was glad about the updated valve seals, as this was a more probable cause of the blow-by.

I have put a few thousand miles on the bike since the repair, and still no sign of an oil leak, but I will continue to monitor the condition of the bike and will update this article if anything changes.


It wasn’t long after the posting of this article that oil started to collect on the right side of the engine again. After searching for the source, I quickly determined that the oil leak on my Sportster was coming from the bottom of the air filter housing. Even though the Harley Davidson is still under warranty, a different Sportster blow-by repair was in order.