Mower is smoking white smoke

Symptoms

• Smoke is white or light gray, not black
• Smoke usually appears at startup and lessens after warming up
• Oil level may be higher than it should be
• Mower may have been tipped on its side recently

Likely causes

• CommonOverfilled crankcaseToo much oil gets pulled into the combustion chamber and burns off as white smoke.
• CommonMower tipped the wrong wayTilting with the carburetor down lets oil flow into the cylinder or air filter.
• PossibleWorn piston rings or valve sealsOn older engines, worn internals let oil seep into the combustion chamber continuously.
• Less commonClogged crankcase breatherA blocked breather tube can pressurize the crankcase and force oil past seals.

What to do

1. Check the oil level with the dipstick and drain any excess down to the correct fill line.
2. If the mower was recently tipped, check the air filter for oil contamination and clean or replace it.
3. Let the engine run for a few minutes; smoke that clears up after warm-up is often just excess oil burning off.
4. If smoke continues steadily and doesn't reduce, the engine may have worn rings or seals letting oil into the cylinder.
5. Avoid tipping the mower with the air filter/carburetor side down in the future; always tip with the spark plug side up per the manual.
6. If smoking persists after correcting the oil level, have a small engine mechanic check compression and internal wear.

Tools and parts

• Dipstick/oil container

When to call a pro

Persistent white smoke after correcting the oil level usually means internal wear that a small engine shop should diagnose.

Safety