How to Clean a Lawn Mower Cylinder Head: A Step-by-Step Guide?

The sweet smell of freshly cut grass, the rhythmic hum of the engine, and the satisfying feeling of a well-maintained lawn – these are the joys of owning a lawnmower. But what happens when that hum turns into a sputtering cough, or the mower starts losing power? A dirty cylinder head could be the culprit! This crucial part of your engine needs regular cleaning to maintain optimal performance. In this comprehensive guide, we’ll break down the process of cleaning a lawn mower cylinder head, from identifying the problem to reassembling your engine like a pro.


A dirty cylinder head can cause a range of problems in your lawn mower, from reduced power and difficulty starting to complete engine failure. The process of cleaning it involves removing the cylinder head, carefully cleaning it, and then reassembling it. This guide will provide step-by-step instructions and helpful tips for a successful cleaning process.

Identifying the Need for Cylinder Head Cleaning

Before jumping into the cleaning process, it’s important to determine if your lawn mower actually needs a cylinder head cleaning. Here are some common signs that indicate a dirty cylinder head:

Symptoms of a Dirty Cylinder Head

  • Reduced engine power: The mower struggles to maintain speed or bogs down when cutting thick grass.
  • Difficulty starting: The engine cranks but doesn’t fire up easily, or it may start and stall shortly after.
  • Backfiring or misfiring: The engine makes popping or sputtering noises.
  • Excessive smoke: Blue, black, or white smoke coming from the exhaust indicates incomplete combustion, often linked to a dirty cylinder head.
  • Fuel consumption: Noticeably higher fuel consumption can point to a dirty cylinder head.

Preparing for the Cleaning Process

Now that you’ve identified the issue, it’s time to prepare for the cleaning process. This involves gathering the necessary tools and ensuring safety precautions are in place.

Tools and Materials

  • Screwdrivers: A set of flathead and Phillips screwdrivers.
  • Wrench set: A variety of metric wrenches.
  • Socket set: A set of sockets, including a spark plug socket.
  • Cleaning tools: A small scraper, a wire brush, a toothbrush, and microfiber cloths.
  • Degreaser: A safe and effective degreaser specifically designed for engine parts.
  • Protective gear: Gloves, safety glasses, and a face mask.
  • Work space: A clean, well-lit area with adequate ventilation.

Safety Precautions

  • Disconnect the spark plug wire: Prevent accidental starting during the cleaning process.
  • Wear protective gear: Protect yourself from potential hazards, including chemicals and sharp tools.
  • Work in a well-ventilated area: Avoid inhaling harmful fumes.
  • Be aware of moving parts: Always handle the cylinder head and other components with care.

Disassembling the Cylinder Head

Once you have your workspace ready and safety gear in place, it’s time to dismantle the cylinder head. This requires a methodical approach to ensure proper reassembly later.

Removing the Cylinder Head

  1. Locate the cylinder head bolts: These are typically located around the cylinder head, attaching it to the engine block.
  2. Loosen the cylinder head bolts: Start by loosening each bolt a small amount before fully removing them.
  3. Remove the cylinder head: Gently lift the cylinder head off the engine block, being careful not to damage any components.

Inspecting the Cylinder Head

  • Check for damage: Look for any cracks, chips, or other signs of wear on the cylinder head.
  • Inspect the valve seats: Make sure the valve seats are in good condition and free of debris.
  • Examine the valves: Inspect the valves for wear, damage, or carbon buildup.

Cleaning the Cylinder Head

Now comes the crucial part: cleaning the cylinder head. This involves removing all the carbon deposits and debris that have accumulated over time.

Removing Carbon Deposits

  1. Degreasing the cylinder head: Apply a generous amount of degreaser to the entire cylinder head, ensuring all surfaces are covered.
  2. Scrubbing the carbon: Use a scraper, wire brush, or toothbrush to remove stubborn carbon buildup from the cylinder head, valve seats, and valves.
  3. Rinsing the cylinder head: Thoroughly rinse the cylinder head with water, ensuring all degreaser and debris are removed.
  4. Drying the cylinder head: Allow the cylinder head to air dry completely.

Cleaning the Valves

  1. Remove the valves: Gently remove the valves from the cylinder head.
  2. Clean the valve stems: Use a wire brush or toothbrush to clean the valve stems and remove any carbon buildup.
  3. Clean the valve heads: Use a small scraper or wire brush to clean the valve heads and remove any carbon deposits.
  4. Inspect the valve seals: Examine the valve seals for wear or damage. If necessary, replace them.

Reassembling the Cylinder Head

After thoroughly cleaning the cylinder head and valves, it’s time to reassemble everything back into place.

Assembling the Cylinder Head

  1. Install the valves: Gently insert the valves back into their respective seats, ensuring they are properly aligned.
  2. Install the cylinder head: Carefully position the cylinder head back onto the engine block, ensuring it is aligned correctly.
  3. Tighten the cylinder head bolts: Gradually tighten the cylinder head bolts in a star pattern, ensuring even pressure distribution.
  4. Torque the bolts to specification: Refer to your lawnmower manual for the recommended torque specifications for the cylinder head bolts.

Final Touches

  1. Reconnect the spark plug wire: Ensure it is properly secured.
  2. Start the engine: After reassembling the cylinder head, start the engine and check for any leaks or problems.
  3. Test the engine performance: Run the engine for a few minutes and observe its performance. The mower should now run smoothly and with increased power.


Cleaning a lawn mower cylinder head is a relatively straightforward process that can significantly improve your mower’s performance. By following these steps and taking proper safety precautions, you can keep your lawn mower running smoothly and efficiently for years to come. Remember to regularly inspect and clean your mower’s engine components, including the cylinder head, to ensure optimal performance and a long lifespan. With a little effort and attention to detail, you can enjoy the benefits of a clean and powerful lawn mower, all while extending its life and saving yourself money on costly repairs.

Frequently Asked Questions

1. Why do I need to clean my lawn mower cylinder head?

Cleaning your lawn mower cylinder head is essential for maintaining its performance and lifespan. Over time, carbon buildup, dirt, and debris can accumulate inside the cylinder head, hindering combustion efficiency and leading to engine problems like misfires, rough idling, and reduced power. Regular cleaning ensures smooth airflow, efficient fuel burning, and optimal engine performance.

A clean cylinder head also helps prevent wear and tear on the engine components. When debris and carbon deposits accumulate, they can cause friction and damage to the piston rings, valves, and other critical parts. Cleaning these components regularly can help extend the life of your lawn mower engine and reduce the risk of costly repairs.

2. What tools do I need to clean a lawn mower cylinder head?

Cleaning your lawn mower cylinder head requires some basic tools commonly found in a home garage. You’ll need a socket wrench set, a flathead screwdriver, a wire brush, a scraper, a rag, a can of carburetor cleaner, and a small container for collecting fluids.

While these are the essential tools, having a few optional items like a vacuum cleaner, a compressed air source, and a small brush can make the cleaning process more efficient and thorough. You might also consider wearing gloves and eye protection for safety during the cleaning process.

3. How often should I clean my lawn mower cylinder head?

The frequency of cleaning your lawn mower cylinder head depends on several factors, including the age and type of your mower, the quality of the fuel used, and the frequency of use. As a general guideline, it’s recommended to clean the cylinder head at least once a year.

If you notice any performance issues like misfires, rough idling, or decreased power, it’s a good indication that your cylinder head might need cleaning. You can also check the spark plug condition; excessive carbon buildup on the spark plug suggests a need for cleaning the cylinder head.

4. Is cleaning a lawn mower cylinder head a difficult process?

Cleaning your lawn mower cylinder head is a relatively straightforward process, even for beginners. The steps involved are simple and require basic mechanical knowledge. With the right tools and a clear understanding of the instructions, you can easily clean your cylinder head without professional help.

If you’re unsure about any steps or feel uncomfortable tackling the cleaning process, it’s always best to consult a qualified mechanic. They can provide guidance and ensure the job is done correctly, preventing potential damage to your lawn mower.

5. Can I use household cleaners to clean the cylinder head?

Using household cleaners for cleaning your lawn mower cylinder head is strongly discouraged. These cleaners are typically designed for different purposes and might damage the engine components or leave harmful residues.

Instead, opt for specialized cleaners like carburetor cleaner, which is specifically designed for cleaning engine parts and removing carbon deposits without harming delicate components. Using the correct cleaning solution ensures efficient cleaning and avoids potential damage to your lawn mower.

6. What should I do after cleaning the cylinder head?

After thoroughly cleaning the cylinder head, it’s essential to reassemble it properly and ensure all components are securely attached. Before starting the engine, make sure the spark plug is correctly installed and the ignition system is functioning properly.

It’s also recommended to check the oil level and top it up if necessary. Finally, start the engine and let it run for a few minutes to allow the engine to warm up and ensure everything is working smoothly.

7. What are some tips for preventing future buildup?

Preventing future carbon buildup in your lawn mower cylinder head requires some proactive measures. Using high-quality fuel with a good octane rating helps minimize carbon deposits. Regularly changing the air filter ensures clean air intake, contributing to cleaner combustion and reduced buildup.

Proper maintenance practices also play a crucial role in preventing buildup. Following the recommended maintenance schedule, including oil changes and spark plug replacement, helps maintain engine health and minimizes the risk of carbon deposits.

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