Why is My Lawn Mower Smoking White? How To Stop It

It worries to see a cloud of white, blue or black smoke coming out of your lawn mower. While it could be something minor, some cases may imply a serious problem that need to be inspected and fixed by an expert. Let’s get down to why your lawn mower is smoking and how to stop it.

Your lawn mower is smoking for a number of reasons depending on the color of the smoke. White or blue smoke is usually linked to oil spill on the engine. Black smoke on the other hand implies a problem in the fuel system all the way to the combustion chamber.

Why is my Lawn Mower Smoking?

A cloud of smoke around your mower’s engine is something that should not be ignored. There could be a major problem behind it which can lead to severe damage of your machine. Fortunately, you can easily identify the reason for a smoking lawn mower by looking at the color of the smoke.

Let’s get to details by explaining the meaning of smoke coming from your lawn mower based on its color.

Lawn Mower Blue/White Smoke Meaning

A white or blue smoke from your mower usually indicate an oil spill on the engine. The oil will then burn forming a cloud of white or blue smoke. Oil is important addition to engine, it minimizes friction and wear between components. Some types of oil are also designed to clean engine.

Oil spill to the engine usually happen during servicing as the old oil is removed and a new one is added into the crankcase. Overfilling the reservoir with oil can also result to leaking due to pressure. For every engine, there is always a mark at which oil should not go beyond.

Oil can also escape the crankcase when mowing on a slope greater than 15 degrees angle. The same can happen when a mower trips to the side during storage, cleaning the mowing deck or sharpening lawn mower the blades.

There is no serious fix required for this kind of problem other than just letting the oil burn until the smoke disappears.

Other reasons for oil spill on the engine include damages to the crankcase, a rapture in breather tube or worn out cylinders and/or piston rings. A blown head gasket will also lead to oil-soaked air filter. These are serious problems that need to be inspected and fixed by an expert before running the engine.

Lawn Mower Smoking Black Meaning

Black exhaust smoke from your lawn mower means that the ratio of gasoline to air is not met for proper combustion. In other words, black smoke shows that your mower has too much fuel than air required for complete combustion. There will be unburnt fuel in the combustion chamber which gets out as black smoke.

Dirty air filter are usually the main reason for insufficient air in the combustion chamber. Cleaning or replacing air filters can help solve the problem. If this does not help, then the carburetor is not supplying the right air/fuel mixture to the combustion chamber of engine.

A dysfunctional carburetor need to be adjusted by an expert or yourself after you have read and understood how it’s done in the manufacturer’s manual.

Pro tip: It is important to know that all mowers with internal combustion engines operate on the same basic principles, but the configuration of their parts varies depending on model or manufacturer.

Lawn mower smoking black could also happen as a result of a low grade fuel or impurities in the oil. This can also be noticed by a lawn mower smelling like gas or production of low engine power. Lawn mowers are recommended to use fuel with a minimum octane rating of 87. Less than this can result to issues.

Black smoke from your lawn mower is also a sign of bad spark plugs. They are what produce the spark that ignites the air/fuel mixture, creating the explosion which makes the engine produce power. If they are worn out or damaged, then a lot of fuel will escape unburnt inform of a black smoke.

How to Stop a Lawn Mower from Smoking

You can stop your lawn mower from smoking white or black through a number of ways.

1. Avoid overfilling the oil/fuel reservoir

Always check the level of oil using the provided dipstick on the reservoir. To do this wipe off the provided dipstick with a rag, and reinsert it into the reservoir and remove to check the level of oil. Ensure it is not exceeding the ‘fill’ line on the stick.

2. Avoid tilting your mower to less than 15 degrees angle

When storing or servicing your lawn mower avoid tilting it to less than 15 degrees angle. If this happens when mowing on slopes, then ensure the spark plugs are facing upwards. This will help in preventing oil from escaping the crankcase and getting onto the engine.

Most four-stroke lawn mower engines require fresh unleaded gasoline with a minimum octane rating of 87 or higher and containing up to 10% ethanol. Two stroke-engines will use the same type of fuel but with addition of a 2-cycle engine oil in a recommended ratio.

4. Check the condition of the piston rings, cylinder, and the head gasket

It is normal for piston rings, cylinder and head gasket to wear out. These parts should be inspected especially during servicing and be repaired or replaced where necessary. Professional service will be much helpful in inspecting and replacing the worn out or damaged parts of your lawn mower.

5. Clean or replace air and oil filters

Filters are helpful in ensuring that impurities are trapped from air and oil before getting into combustion chamber of the engine. Dirty or clogged filters become dysfunctional and there is need to clean or replace them as directed in the manufacturer’s manual.

6. Adjust the carburetor

A carburetor provides the right air to fuel ratio before the mixture is taken for combustion in the engine. If you lawn mower is smoking black then try to adjust the carburetor as directed in the user manual.

7. Clean or replace spark plugs

When servicing your lawn mower, you should also remember to check the state of your spark plugs. Clean or replace them to avoid high fuel consumption, stop black smoke from your lawn mower and increase the power of your engine.

8. Proper storage during winter

Lawn mowers are only deployed when grass is actively growing. During cold seasons, little or no mowing takes place. Always winterize your lawn mower before storing it for winter. This will give you easy start when the mowing season comes.

Final Thought

A black, blue or white cloud of smoke from a lawn mower should be inspected even if it doesn’t mean something serious. You could end up replacing the entire engine by ignoring this. If you don’t have skill to deduce the problem an expert should be able to help. Above all, run and maintain your lawn mower as directed in the manufacturer’s manual.

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