Smoke is the easiest symptom to see when it comes to your engine having some issues. While it may look bad, an engine blowing smoke is often not a serious malfunction, but it can turn into something worse if left to its own. Different colors of smoke can indicate different problems with your engine.
This is generally caused by an issue in the carburetor and fuel systems. The usual cause is a fuel-to-air mixture that is too rich, meaning it has more gasoline in the mix than it should. This in itself can have two probable causes – either your air filter is clogged, or your carburetor needs to be tuned.
You’ll first want to check the air filter, as it is the easiest to diagnose and fix. Simply remove the air filter and clean it, or replace it if it is clogged. Once this has been completed, start up your mower again and see if the problem has been fixed
If your mower is still emitting black smoke after this step, the next step is to adjust the carburetor to produce a leaner fuel-to-air mixture. You will need to consult your owners’ manual for instructions for your specific mower and carburetor. Generally, it is as simple as turning a screw or two.
If these two steps do not fix the problem, we would suggest taking your mower in for service, as it may be something more complex that will need expert diagnosis.
Blue or White Smoke
While black smoke is caused by the burning of more fuel than air, blue or white smoke is generally caused by the burning of excess oil. Often, the cause of this smoke is something simple that doesn’t need to be addressed. Engines have certain tolerances of angles for operation, and an engine that contains fluid that is tilted or turned over can allow some of the oil to leak out. When this is the case, the oil will then burn off, creating smoke. It won’t last long, and the best thing you can do is allow the engine to keep running and burn off the excess – turning off the engine just means it will smoke when you start it up again. The same thing can happen if you overfill your oil reservoir, and it has the same solution – just burn it off.
If this is not an intermittent problem, it is something more in-depth. Check your crankcase and see if there are any air leaks, as this can allow more air into the crankcase than needed, causing a higher oil mist than your crankcase’s breather can handle, leading it to be burned off. If you cannot detect any leak, and your mower suffers in terms of performance, it is unfortunately necessary to take the mower to a skilled mechanic. Often times this color of smoke is caused by a blown head gasket, a worn cylinder or worn rings, or an inoperative crankcase breather, all of which will need help from a professional.
So remember, just because your mower is smoking doesn’t mean it’s broken – it just may need a little bit of care. Look at the color and smell the smoke before you take it in for repairs – it could be the difference between buying a cheap air filter or spending big money on parts and labor.