How to Troubleshoot Gas in the Crankcase of a Lawn Mower

Gas is not supposed to be inside a lawn mower's crankcase. However, most of the reasons why this occurs will not cost you more than a few dollars to fix. Many small, different pieces may be causing gas to get into the crankcase. These pieces may not even be broken, but simply may need adjusted. Just take your time when inspecting every piece and look for any errors.

Adjustable wrench
New seat kit

Instructions

- 1
  Look at the air filter. If you recently dripped a little gas on the filter as recommended by the owner's manual, a little bit of gas will get into the crankcase, which is no problem at all.
- 2
  Inspect the float valve. If the float valve is cracked, gas will flow into the crankcase. The float valve is located off the carburetor and looks like a bullet. Pay close attention to the pointed end, as that is the common part that cracks.
- 3
  Tighten all bolts on the crankcase and on the seat kit that sits above the carburetor. If these pieces are loose, gas can get into the crankcase.
- 4
  Replace the seat kit if it appears broken. You may have to use a tap and a bolt to remove the seat kit. Read the owner's manual to see if you need it.

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