Why is my lawn mower blowing white smoke?

Why is my lawn mower blowing white smoke?

Every gardener and therefore lawnmower owner at some point have problems with their mowers and colored smoke that's coming out of them. The most common one is the white smoke. It's normal to get worried when something like this happens especially if you have 4 stroke mowers because they shouldn't smoke from exhaust at all. Most of that white smoke will be gone soon probably, but if you don't do anything about that in the future, next time it won't go away that easily and you will have a problem. Sometimes engine oil can go inside into the combustion ventricle of the engine but you can simply fix that just by letting the mower idle for some time until the smoke disappears. Other causes probably will take more time to fix and in some cases, you will be forced to ask a professional mechanics for help. In this article, we will explain some of the reasons why your mower exhaust white smoke and how to fix it. 


Using a mower at a steep angle 

If you use your mower at a steep angle or constantly tipping it, the engine oil will just pour into the cylinder and start burning. This is one of the most common cases where your mower will exhaust white smoke. Also, many people turn the mower on the side or its back while they checking or replacing blades. This is very wrong, and just like in the case before, oil will go inside the cylinder and you will have a problem. 

In this case, you can fix this pretty easily. Just let the mower idle to burn up the oil that ended up in the combustion ventricle completely. If you must replace blades or for some reason look below your mower, use the owner’s manual for right instructions on how to do it. Avoid using your mower in areas with a slope greater than 15 degrees and you'll be okay. 


Too much oil in the engine

Engine oil is very vital for any mower, it helps your mower's engine to last longer and works perfectly. Changing the oil is a regular routine for every gardener but in this routine, you need to be pretty precise to add the recommended quantity, not to overfill or at some point putt less oil than it's needed. Mower with less oil will have problems with friction due to lack of lubrication. Mowers with too much oil, on the other hand, will have the same problems as in the case before. Oil will go into the combustion ventricle and start burning. As a result, your whole garden will end up in white smoke. Also, too much oil won't cause only smoke issues but also will slow down your mower and it will take much longer to start. 

Preventing this problem is also simple, just try not to add to much oil in your mower as the first step. Also, use the owner’s manual and look for information about how much oil you mower need. A regular mower won't need more than 20 ounces of oil. Once you pour the recommended amount of the engine oil use dipstick to check if everything is okay. In case you already pour too much oil in your mower, you will have to drain all engine oil from the engine and pour again right amount. 


Problems with head gasket

While with the first two issues you can deal pretty easily, this one will be a little bit harder. Leaking or damaged head gasket is a serious problem and the reason why your mower exhaust white smoke. The Head gasket keeps the engine and is located in the area which connects the cylinder with the rest of the machine. If the head gasket is broken and not sealing the cylinder properly, oil will easily go through the cylinder. As the oil goes inside it will start burning and cause white smoke. Smoke will be even bigger if the mower continues to work. Also, you will notice the oil all over the head gasket and body of your lawnmower. 

When it comes to fixing, the head gasket is a very vital part of the mower, so if it's damaged or leaking you will have to buy a new one and replace it. They aren't too expensive, for just a few dollars you can get a new one, and if you work on small machines like this one before, you will be able to replace it by yourself. 

Remove sparkplug wire together with bolts that keep the cylinder. The next thing you should do is to take off the damaged gasket and all their remaining pieces but be careful not to damage the surface. After that put the new gasket on its position and also place back the cylinder head.


Problems with piston rings

This problem is probably the worst one you can have with your lawnmower and it's usual for older mowers or ones who are poorly maintained. The main role of piston rings is to control the amount of oil, and very little of that amount goes to the piston rings in order to move them nicely inside the machine. If your piston rings are broken for some reason, there is nothing to stop the oil from pouring inside the combustion ventricle and causing burning and white smoke. The most common reason why your piston rings are in bad shape is the unclean air filter and if you didn't replace oil at the right time, it can also damage your rings. 

Fixing this problem won't be easy like previous ones. Your whole engine must be open during repairing. If your mower had rings in very bad condition it's very likely that the head cylinder will be also damaged and need to be replaced. This kind of work you probably won't be able to do on your own, so better look for professional help or simply install a completely new engine.


Oil in the fuel of a four-stroke mower

If you are a four-stroke mower owner, read this carefully. Mixing oil in the fuel of these mowers is strictly forbidden. These modern mowers come with 4 stroke engines and are more durable and stronger than mowers with 2 stroke engines. You will also have fewer worries about maintenance. The problem is if you put the oil in your fuel. When you start your mower it will burn that oil you put and produce a lot of white smoke. Turn off your mower immediately because if the engine keeps running it can lead to huge damage. 

When it comes to fixing this problem, it also depends on how much oil did you mix with the fuel. If we talk about a smaller amount then the oil will just get dissolved in the fuel, but if it's a bigger amount of oil then you must remove the fuel completely from the tank and pour a new one without any oil inside. 


Final thoughts

To sum up, we recommend you to read the owner's manual before any action with your lawnmower. And if you wonder why, the answer is pretty simple, to avoid and unnecessary costs and problems. Not all mowers are the same and each of them has its own characteristics and peculiarities. Do like we said, and you won't have any problems with white smoke from your mower.