External Inspection
An external defect can be the source of an oil leak on a Craftsman lawn mower. You could have a crack in the crankcase, which houses the oil prior to starting your engine. If is oil anywhere on the crankcase, wipe it clean and closely inspect the spot for a crack. You should also check any places where oil enters or exits the mower such as the oil drain holes and fill port. Larger Craftsman mowers and lawn tractors might also be equipped with oil filters. Ensure that they are closed tight and that any residual oil is wiped off of them. Once all external oil spots are cleaned and the physical check is done, run the mower for five minutes and then check again for leaks.
Overflow
Craftsman riding mowers and lawn tractors have slope recommendations for operation. These mowers should typically not be operated on a grade steeper than 15 degrees. If you operate your Craftsman on these slopes, you run the risk of oil flowing from the crankcase and into the combustion chamber. Any unlit oil will spill into the exhaust and muffler areas, causing smoke during combustion. For Craftsman push and walk-behind mowers, be careful when storing or servicing your mower not to tilt the engine in the wrong direction. If you drain your oil through the oil fill port on the engine, ensure the air filter is pointing up when you tilt the engine or oil can spill into the combustion chamber.
Breather System
Briggs and Stratton engines on the larger push mowers and riding mowers are equipped with a breather system that aids in cooling the engine. The breather system is typically composed of a breather tube that allows air and oil to pass over the combustion section to cool and transfer heat. Oil is returned to the crankcase after passing through it. If the breather system is damaged or a part of it malfunctions, oil can back flow into the tube, clogging the air filter. The clogged filter can create pressure inside the combustion chamber and blow the gasket seals, allowing oil in.
Maintenance
To help prevent oil leaks, follow the recommended maintenance schedule as shown on the Briggs and Stratton engine owner’s manual. Check the oil before every use to ensure it isn’t filled beyond capacity. Also change the oil on schedule, which is usually after 25 to 50 hours of operation or every season. Oil has natural contaminants that, over time, can clog filters and engine plumbing. Dirty oil also loses cooling and lubrication properties, which can add up to an overheated engine.
