How-To Change the Air Filter on a Walk-Behind Mower (Briggs and Stratton Sprint, Classic and Quattro Engines)
Before you start this project, make sure you have the correct filter for your engine. Many filters look alike; refer to the engine owner's manual to ensure that you have the correct filter for your engine. Some of the steps below may vary depending upon your engine. The steps below are specifically geared towards Briggs and Stratton Sprint, Classic and Quattro engines.
Remove the spark plug wire and ground it against the engine as a safety precaution.
Use a standard head screwdriver to remove the retaining bolt from the air filter housing.
Separate two housing halves and remove the foam filter from the housing. Note the orientation of the housing.
Clear any debris from the filter housing.
Saturate a new foam filter in clean engine oil. Squeeze the filter to remove as much of the oil as possible.
Place the new foam filter into the filter housing base. Install the filter with the proper orientation.
Place the cover over the base and re-install the retaining bolt. Tighten with a slotted screwdriver.