Blown Oil Filler Cap

Question for Fix My Hog I started my 2005 XL1200R this morning, and in a few seconds, it blew the filler cap off the oil tank, and a large amount of oil started running down to the floor. I shut it off right away, then had to catch a ride to the DMV for renewal of my CDL. That took a while, but eventually I got back to look at the mess. The oil tank is still filled to the top with oil. The oil appears to have metal flakes in it. Bike has only 3776 miles on it, and oil has been changed on schedule. What do you think might have caused this? Guess I might need a shop manual or some such to guide me in dis-assembly and repair. Do you have something you might recommend? Got the Sportster DVD, very helpful, thanks. Any help you can provide would be appreciated. Charlie N.

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Fix My Hog Answers Hi Charles, There are way to many variables that could be the cause of a blown oil filler cap. My first guess would be a problem with the oil pump, either way the engine must be removed from the m/c and completely taken apart and cleaned. At this point you should find the cause of your problem. Have there been any recent modifications to the engine? Wrench Safe, Team FMH

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Discussion
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10 Responses to “Blown Oil Filler Cap”
  1. Todd Oesterreich

    “A large amount of oil started running down to the floor”.

    “The oil tank is still filled to the top with oil.”

    Reply
  2. Kevin sale

    I have a 2oo1 roadking twin cam motor makes a lot top end noise has 30.000 on it this normal

    Reply
    • Customer Service

      Dear Kevin,

      Thank you for your patience. In response to your question-

      If you feel like there is excessive top end noise, inspect your lifters. If you have adjustable pushrods, check adjustment.
      Also, inspect your cam chain tensioners.
      https://www.fixmyhog.com/video/cam-chain-tensioner-shoe-inspection-001291/

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.
      https://go.fixmyhog.com/c17233

      Mark
      Fix My Hog

      Reply
  3. Bill

    Worked as a mechanic in a Harley Davidson Dealership for 20 years , seen this happen a few times and before you start tearing the engine apart , I have found that most times the oil tank is over full ,, when you check the oil level ,you should always check it at operating temp. Because oil expands when it gets warm , and you always check oil level on that particular bike with it standing straight up , not on the sidestand ,, therefore if you check the oil cold and on the sidestand , it will it will show low on the stick and if you add oil it will be overfull and heats up it expands and blow the cork out !!!! Just something to keep in mind before you start tearing things apart

    Reply
    • Michael Limehouse

      I am a tech also and this was my first thought. Sportsters come in with overfilled oil tanks. The owners check it cold and overfill it. Very common

      Reply
  4. Danny Clay

    I recently purchased 1999 fatboy( last evolution motor)I’m thinking about synthetic oil instead of conventional oil. What are your thoughts?

    Reply
    • Customer Service

      Dear Danny,

      Thank you for your patience. In response to your question-

      There is nothing wrong with using conventional oil as long as you change the oil every 2,500 to 3,000 miles. If running synthetic, we still suggest replacing by 3,000 miles on an air cooled engine.
      SPECTRO
      https://www.fixmyhog.com/video/spectro-oil-005014/

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first-year membership.
      https://go.fixmyhog.com/c17233

      Mark
      Fix My Hog

      Reply
  5. Mick

    Is your bike CARBY or EFI If it’s carby I’ve encountered this sort of problem before on several occasions on earlier models, where the vacuum fails on the pet cock, and if the needle in the carby doesn’t seat properly it may fill the crankcase with gasoline. Hence the engine will blow it back into the oil tank. Check and smell the oil and see if it’s mixed with petrol? Check your gas tank see if you’re gas level has dropped? To try and remedy this problem you first have to fix the fuel problem and then somehow drain the crankcase. Remember to replace the engine oil and filter. THIS IS ONLY WITH CARBY MODELS. I hope this helps, Cheers Mick (Brookvale Bike Centre Sydney Australia)

    Reply