If you took apart your lawn mower’s engine, you would find dirt and build-up in a whole bunch of different places. This could include grime in the crankcase, carbon build-up in the cylinder head, gum in the carburetor, and then, of course, a mouse nest in the lawn mower engine. So, instead of overhauling your engine and breaking it down into a thousand pieces to clean, why not carry out a few simple cleaning processes instead?
Here’s my go-to method to keep both the inside and the outside of my lawn mower engine clean without breaking down my engine.
Cleaning Your Lawn Mower’s Engine (The Short Explanation)
If you are interested in cleaning your lawn mower engine to extend your mower’s life If you are interested in cleaning your lawn mower engine to extend your mower’s life span and improve performance, then there are several additives and cleaner you can use that don’t require dismantling your lawn mower’s engine. Here are my preferred methods.
- The Exterior of the Engine – Spray Cleaner
- Inside the Crankcase – Chemical Flush
- Inside the Combustion Chamber – Spray Cleaner
- Inside the Carburetor – Spray Cleaner
Why It’s Important to Periodically Clean Your Lawn Mower’s Engine
Where should I start? There are so many problems that are caused by having a dirty engine. Here are just a few symptoms you might have already encountered and some of the potential causes. I kept the list short, but I’m sure you’ll get the idea of why a clean lawn mower engine is so important.
- Spluttering Engine Dirty Carburetor
- Trouble Starting Carbon Build up on Sparkplug
- Overheating Clogged Cooling Fins
- Gas Tank Vacuum Dirty Gas Cap
What You’ll Need to Clean Your Mower’s Engine (Equipment List)
I have broken down the 4 different cleaning processes I use to keep all the different parts of my engine clean. Here’s a list of all the items you’ll need to carry out each process.
Exterior Engine Cleaning
- WD-40 Engine Degreaser
- WD-40 General Lubricant
- Air Line
- Stiff Brush
- Cleaning Cloths
Crankcase Cleaning
- Oil Pan
- Oil Funnel
- Oil
- Sea Foam Motor Treatment
Combustion Chamber Cleaning
- Sea Foam Top Engine Cleaner
Carburetor Cleaning
- WD-40 Carburetor Cleaner
How to Clean a Lawn Mower Engine (Step By Step)
When it comes to how to clean a lawn mower engine, you don’t need wrenches, sockets, or even a screwdriver. As you can see, it’s all pretty easy to do. So let’s jump in and look at each cleaning process and the steps you can follow.
Exterior Engine Cleaning
This process is really a case of cleaning the exterior using a few tools. To start, I blast the engine with my air compressor to remove any loose material like grass clipping and the odd mouse nest. Then, I grab my degreaser and coat the entire engine, focusing on the greasy, oily spots. Next, I allow the degreaser to work its magic and really soak into the bad areas.
Now, you could remove the engine cover if you wanted to, but I find that my air compressor does a good enough job. Ok, next, use a small stiff brush and start working the dirt. An old toothbrush is perfect for this job. Then, I go back and forth between my degreaser and toothbrush until I’m left with just an oily coating on my engine.
Next, I use a shop cloth to start working off the dirt. Finally, I swap over to my WD-40 General Lubricant and wash off the dirt swapping between wiping with the cloth and spray. After a little while, dirt and grime have all gone. Job done, and not once did I need to go in my toolbox, and the engine now has a protective coating as well.
Crankcase Cleaning
So you already know how to drain oil from your lawn mower and how to do an oil change. Well, it’s basically the exact same process, other than it has a couple more steps. The first task is to add a treatment like Sea Foam Motor Treatment into the oil tank through the oil filler cap opening, then run the engine for several minutes.
This allows the treatment to work around the inside of the crankcase and clean away any build-up that may have formed. Once you run the engine long enough, the dirt will be loose and floating in the oil. Now, you need to remove the oil and dirt from the crankcase by doing an oil change. So, this is how to flush a lawn mower engine. Pretty simple, really.
Here’s a summary of the complete steps to flush a lawn mower engine.
- Remove the oil filler cap
- Add treatment into the oil filler opening (follow product instructions for treatment amount)
- Replace the oil filler cap
- Start the lawn mower
- Allow the engine to run (follow product instructions for time requirements)
- Allow the engine to cool
- Tip over the lawn mower the correct way (air filter up)
- Allow old oil to drain
- Upright the lawn mower
- Fill with new oil (lawn mower oil type specific to your lawn mower engine)
- Check oil is filled to the correct level
- Start the lawn mower to circulate fresh oil
- Dispose of old oil safely
Combustion Chamber Cleaning
Next on my list of how to clean a lawn mower engine is how to clean the inside of the combustion chamber. This includes parts like the valves, the cylinder head, and also into the rockers. So the first thing is to start up your lawn mower and allow the engine to warm up. Then, remove the air filter with the engine running and increase your engine’s RPMs.
Next, with the throttle plate open, spray the cleaning into the throttle body of the carburetor so that the spray reaches the inside of the engine. Then shut off your lawn mower’s engine and stop spraying the cleaner after a few seconds. What you’ll want to achieve is leaving just a little spray inside the engine to continue cleaning. This is called a hot clean. Basically, with the engine’s heat and fresh spray, the engine continues to be cleaned.
So, leave the engine for ten or so minutes, then fire up the engine once again. By this stage, the cleaner should have broken down all the carbon deposits, and the engine should now either burn off or push the dirt out of the exhaust pipe.
Now I usually repeat this process a few times to give the inside of the engine a real good clean. But, before you jump into the cleaning process, make sure you check the instructions of the top engine cleaner in case there are any special requirements or if there is a slightly different process.
Carburetor Cleaning
This is the last item on my list of cleaning methods, and it is probably the easiest one of all. So, remove the air filter cover and the air filter, then start your lawn mower. Next, spray a quick blast of carburetor cleaner into the throttle body. For me, I always use the WD-40 Carburetor Cleaner. Then allow the engine to burn off the spray cleaner and give it another blast.
I repeat this process five or six times to get a really good cleaning of my lawn mower carburetor. And that’s it. It’s basically the same as cleaning the combustion chamber, just that you don’t need to get the cleaner deep into the engine this time.
How Often Should You Clean Your Lawn Mower’s Engine?
Well, this is a tough one. It really comes down to how dirty your lawn mower engine gets and how well you look after it. If you are using good fuel and good quality oil, then you might not need to use these four cleaning processes too much. Also, if you wipe up any spillage, the engine’s exterior might not get so dirty.
But as a general rule, I make sure to clean my whole engine every six months. When it comes to the carburetor cleaning, I probably do this every few months. After all, it only takes a minute or two, and it improves how my lawn mower performs.
Leave a Reply