Why is my lawn mower shooting smoke out the side?

you may have blow a seal by overfilling the engine with oil. turning it over to drain it only made things worse, there's a drain plug on the bottom of the engine just like a car. that's what it's there for. take the air filter off, wash it in mild soap and warm water thoroughly, squeeze it out wrapped in a rag, then pour a little bit of that oil that you bought on it, and squeeze it wrapped in the rag once more. put it all back together and start the mower, letting it run for 5 minutes or so. if it still smokes, you may need to take it to be repaired.

What color smoke? White ( oil) or black/grey( gas) - splash oiling push mowers arent supposed to set on thier side, unless theyre empty of fuel and oil. What im thinking is this: when you set it on its side to drain the oil, some oil came out thru the breather vent and into the carb and its burning it there. Check the carb side and make sure its not full of oil (it'll foul the plug if its too oily)- burning some oil this way isnt harmful to the mower - just makes alot of smoke. I agree mowers dont need a whole lot of oil- definitly less then a full quart, even my lawntractors dont take more then a half quart.

Check your air filter! IF it is oily it must be cleaned (foam element) or replaced (paper element)

Most small Briggs engines require 20 ounces of oil to fill the crankcase, **but check your owners manual first!** (a quart is 32 ounces) so it doesn't take much to overfill the engine.

Try starting all over. Remove the air filter, drain the oil, refill using the recommended amount of 30W motor oil. Chances are this will solve the smoking problems.

When you over filled it and than tipped it you got oil into the crankcase vent line which goes to the airbox so the airfilter is now oily.. I have a tecumseh engine that came with the wrong dipstick in it. If you put oil up to the full mark it is way overfilled. You didn't say what engine but most in the 5 hp range take less than a quart.

Sounds like the piston rings are going and oil is leaking into the combustion chamber and is burning off. You better keep a good watch on your oil level. Good luck. ( If it needs rings probably better off buying a new mower.)

A good tune up is needed which means replacing oil,plug,filters.

busted rings will let oil in combustion chamber cause it smoke white smoke , i have one that only smokes when it leans on the side the rings cracked on. is wore out too .

i think your lawn mower might be to hot