What Would Cause My Briggs Stratton Murray Lawnmower to Leak Oil Through the carburetor

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  1. Incorrect Oil Level:

    • Diagnosis: Check the oil level using the dipstick and ensure it’s within the recommended range. If it’s overfilled, drain the excess oil.
    • Fix: Adjust the oil level to the correct amount as specified in the lawnmower’s manual. Be cautious not to overfill or underfill the oil reservoir.
  2. Faulty Crankcase Breather:

    • Diagnosis: Inspect the crankcase breather for clogs or damage. Test its functionality by removing it and checking for airflow. Can lead to rough idling. Misfires:
    • Fix: Clean or replace the crankcase breather if it’s clogged or damaged. Ensure it’s installed correctly to allow proper ventilation.
  3. Worn Piston Rings or Valve Seals:

    • Diagnosis: Perform a compression test to check for worn piston rings. Examine the valve seals for leaks or damage.
    • Fix: If piston rings or valve seals are worn, the engine may require a rebuild or replacement of these components. This is a more involved repair that may require professional assistance.
  4. Blow-by:

    • Diagnosis: Check for excessive smoke from the exhaust and perform a compression test to determine if blow-by is occurring.
    • Fix: Addressing blow-by may involve replacing worn piston rings or addressing other internal engine issues. Consult a professional mechanic for assistance.
  5. Improper Storage or Tipping:

    • Diagnosis: Consider the lawnmower’s storage conditions and whether it has been tipped or stored at an angle. Tipping like the picture, the lawn mower will smoke bad for a little then clear up.
    • Fix: Store the lawnmower in a level position and avoid tipping it excessively. If already tipped, allow the lawnmower to sit in a level position for some time to allow oil to settle back into the crankcase.
  6. Incorrect Type of Oil:

    • Diagnosis: Verify that the correct type and viscosity of oil are being used in the lawnmower engine.
    • Fix: Drain and replace the oil with the appropriate type and viscosity recommended by the manufacturer.

Remember to always consult the lawnmower’s manual for specific maintenance procedures and specifications. If you’re unsure about performing any repairs or diagnostics, seek assistance from a qualified small engine mechanic or a friend who understands mower mechanics.

One comment

  1. Thank you very much for sharing, I learned a lot from your article. Very cool. Thanks. nimabi

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