Oil Leak on Harley

Q: I have 89 FXRS I guess it`s a bottom breather, I just bought an ultra lower set of cases. I had the crank & rods installed, I installed a set of 3&5/8 jugs & pistons, S&S heads top breather! Now I have oil blowing all over the engine?I need some DVD to help me solve this???? can you help me with this oil leak on Harley? Dennis D.

A: Dennis, It sounds like you have a lot going on here. I am assuming that the oil is blowing out of your top breather bolts. The cases would need to be bottom breathing. Are they? Also, were the heads new or used? If they were used, do you have any idea what condition they were in? Check to see if the timing mark on your breather gear is correctly aligned with the correct cam gear timing mark. Also, you can pull your rocker boxes to check your umbrella valves. They should be on the intake side. If you are in your cam compartment, be sure your oil pump is working correctly. Check the condition of your pinion gear. These are just a few things that come to mind. Good luck

Videos: Cam Class
  • (will not be published)

17 Responses to “Oil Leak on Harley”
  1. Allen

    Sounds like my FXRS-SP and that nasty idea of a check valve that never works on 1990 models? Let it sit and it pumps oil out of breather pipe or in your case up to the air cleaner?

        • Allen

          fxrs-sp forgot S&S Stroker kit complete. Only stock item left was cases which were bored for large cylinders. Stock oil pump. Stock leaky 1990 evo check valve and spring.
          The fix for this sump problem was a mini 1″ x 1″ x 1/2″ 12vdc pump from Amazon, (search bar put mini oil pump) oil and gas proof attached to bottom breather pipe and thru a check valve returned to return oil line to oil tank.
          How was that fix? HEW-YAH !!!

  2. Dennis Wells
    Dennis Wells

    My 2005 Harley Ultra classic leaks transmission fluid when its on its side. I am old and let it lay down while sitting at a stop light. Not on purpose. before I could get it up, tranny fluid was pouring out the side cover

  3. Duane Mitchell
    Duane Mitchell

    I too have a leak but it’s on my 2006 roadking classic . On the bottle of the primary crankcase after a stater and voltage regulator change

  4. bob burnett
    bob burnett

    my 2003 xlh leaking primary fluid when on kick stand..I have recently put on forward controls..Hope that didnt cause it,,dont see how it could.

  5. Karl

    I have some oil leaking around my rocker box covers. I need to take the heads off or the motor out to replace these gaskets? 1981 superglide stock

  6. Daniel Morgan
    Daniel Morgan

    I know it’s not emissions legal but vent those heads to atmosphere instead of your breather. When you squeeze out the bore with a sidewinder this can be a problem. You might even want to run two separate breather hoses.

  7. Ricky Jamison
    Ricky Jamison

    I have a Electra limited 103 engine and I am a little oil from my breather. Do you have any idea of what is causing this?

    • Customer Service
      Customer Service

      Hello Ricky!

      That’s a great question!

      The ‘Ask an Expert’ section is currently for members to our online community. We do have a promotional offer if you are interested. This would include access to expert advice (like this), plus discounts, hours of Premium videos, etc. Please feel free to take a look. You can message us right back with your question if you decide to become a member and you will have a response within 1-2 business days from our experts!

      Please follow the steps below to receive the annual membership at the introductory rate:

      1. Click on the email link: https://go.fixmyhog.com/c18236
      2. Click on the Premium Membership offer.
      3. The Checkout page will display your Premium Membership purchase.
      4. Fill in your Billing Details and create an account password.
      5. Fill in your debit/credit card information.
      6. Finish by clicking Complete Order.

      If you have any further questions, please contact Customer Service at 1-855-231-0653 at your earliest convenience, or chat with us on our site.

      We greatly appreciate your business!


      Fix My Hog Video Membership

  8. Darryl Lee
    Darryl Lee

    I have 79 low rider FXS, after sitting for awhile it throws up oil through breather tube while kick starting. Back in the day everyone would run breather tube down to the bottom between engine and transmission.

    • Customer Service
      Customer Service


      You can try removing the oil pump check valve ball & spring.
      Clean the ball bearing and the oil pump bore, then stretch the spring about 1/4″ longer.
      Use a drag link or a chisel to unscrew the cap of the taller tower on the oil pump to access.
      If the bike continues to sump often or excessively, you will likely need to replace your oil pump.


      Fix My Hog


    Make sure you have the air/oil separator in place-inside the tube inside of the nose cone is where it goes. ALSO-vital to have the CORRECT nose cone gasket ! Ask me how I know. Had the same issue when I put the EV27 in, even being careful.