How to Maintain Small Engine Gas-Powered Yard Tools

From lawnmowers to leaf blowers, you probably have quite a few small-engine, gas-powered tools in your yard. These tools are not invincible, so to keep them in top condition and save money on repairs and replacements, you need to learn how to take care of the tools and their engines. In this video, This Old House landscape contractor Roger Cook walks us through some key maintenance techniques for both two-stroke and four-stroke engines.

Small Engines: The Basics

Learning and understanding how small engines work will help you take care of them better while reducing the risk of damage to your engine or equipment. Small engines, whether two-stroke or four-stroke, have common elements, but their differences are necessary to take into account during maintenance.

Four-Stroke Engines

Four-stroke engines, which are usually installed in lawnmowers and some larger yard tools, operate on a four-step cycle:

1. Intake: The piston moves down, drawing in a mixture of fuel and air.
2. Compression: The piston moves up, compressing the fuel-air mixture.
3. Combustion: The spark plug ignites the compressed mixture, forcing the piston down. This is also called the power stroke.
4. Exhaust: The piston moves up, expelling the burnt gases. Then the cycle begins again.

These engines have separate fuel and oil systems. The oil is stored in the crankcase to lubricate the engine’s moving parts. For the best performance, it’s important to keep the engine full of oil at all times.

Two-Stroke Engines

Two-stroke engines, often used in smaller tools like string trimmers and leaf blowers, complete their cycle in just two piston movements:

1. Upstroke: Fuel-air mixture is drawn in and compressed.
2. Downstroke: The mixture is ignited, and exhaust gases are expelled.

Unlike four-stroke engines, two-stroke engines mix oil with fuel for lubrication, so there is no need for a separate oil reservoir. This simple setup makes for a lighter and more compact engine, which is great for handheld equipment where weight and size impact how well the job gets done.

Important Tasks for Gas-Powered Yard Tools

Regular maintenance is key to keeping your gas-powered yard tools running smoothly. These tasks are straightforward but require consistency to be effective. The following maintenance tasks are important for keeping your tools working. Make sure to follow a consistent care plan to avoid expensive repairs or replacements.

Spark Plug Maintenance

A faulty spark plug can cause starting issues or poor engine performance. To keep it working:

1. Remove and inspect the spark plug each season.
2. Replace it if it shows signs of wear or damage.
3. For safety, always disconnect the spark plug wire when working on the equipment.

Air Filter Care

A clean air filter ensures your engine receives the right amount of clean air for combustion. A clogged air filter restricts airflow, leading to engine strain and reduced performance. Here’s how to take care of your air filter:

1. Inspect the air filter frequently.
2. Clean or replace it when it becomes dark and dirty.
3. For foam filters, wash with soap and water, then lightly oil before reinstalling.

Oil Management

Four-stroke engines rely on clean oil for lubrication to prevent wear and overheating. Regular oil changes reduce the risk of engine damage and keep it running smoothly.

1. Check the oil level before each use.
2. Assess the oil’s condition – it should be clean, not ultra-dark.
3. Change the oil regularly by tipping the machine or using the drain plug.
4. Always recycle used oil properly.

Fuel Considerations For Small Engine Yard Tools

The fuel you use and how you store it can significantly impact your tools’ performance and longevity. Proper fuel management prevents issues related to stale or contaminated fuel.

Choose the Right Fuel

Read the tips below to help you pick the right fuel for your work:

1. Use high-octane fuel for better performance and cleaner burning.
2. Mix oil with fuel at the correct ratio (often 50:1) for two-stroke engines. Correct oil-to-fuel ratios prevent lubrication problems that could lead to engine failure. 
3. Avoid using fuel with ethanol content higher than 10% (E10) unless specified by the manufacturer.

Fuel Storage and Treatment

Stale fuel can cause starting problems and damage engine components. Make sure your fuel is properly stored to prevent degradation and so that your engine reliably starts, even if you don’t use it for a while:

1. Store only enough gas for 4-6 weeks of use for freshness.
2. Use fuel stabilizers to extend the shelf life of stored gas.
3. Consider using a blue stabilizer to address ethanol-related water issues in modern fuels.

Seasonal Maintenance Tips for Small Engine Yard Tools

Different seasons require specific approaches to keeping your tools in working order. Switch up your care plan as the seasons demand it with the following suggestions.

Spring Preparation

Spring is an important time to revive your tools from winter storage, especially as you prepare for the growing season:

1. Change the oil in four-stroke engines.
2. Replace or clean air filters.
3. Inspect and sharpen blades on cutting tools.
4. Check fuel levels and freshness.

Summer Upkeep

You’ll probably be using your tools a lot throughout the summer, so make sure you’re doing regular maintenance to prevent overheating and breakdowns. During heavy use periods:

1. Clean grass clippings and debris after each use.
2. Check and tighten all bolts and screws regularly.
3. Lubricate moving parts as recommended by the manufacturer.
4. Monitor oil and fuel levels frequently.

Fall Protection

Winterizing your tools prevents damage from stale fuel and moisture. Before storing tools for winter:

1. Run the engine until the fuel tank is empty, or add a fuel stabilizer.
2. Clean all exterior surfaces thoroughly.
3. Store tools in a dry, protected area.
4. Remove and inspect spark plugs.

Troubleshooting Common Small Engine Gas-Powered Yard Tool Issues

Even with regular maintenance, you can have issues with your engine. Here are some common problems and their solutions:

Engine Won’t Start

A non-starting engine often indicates fuel or ignition problems. If your engine refuses to start:

1. Check for fresh fuel and proper fuel mixture.
2. Inspect the spark plug for fouling or damage.
3. Keep the air filter clean and unobstructed.

Poor Performance

For engines that run poorly, fixing the air and/or fuel flow usually addresses the issue:

1. Clean or replace the air filter.
2. Check for fuel line blockages.
3. Inspect the exhaust port for carbon buildup.

Excessive Vibration

Vibration can indicate a mechanical imbalance or internal wear and tear. If you notice unusual vibration, identify and fix the source of the problem immediately to prevent further damage and keep yourself safe:

1. Make sure all mounting bolts are tight.
2. Check for loose or damaged blades.
3. Inspect the crankshaft for straightness.

Materials

• Gas can (1 gallon)

Tools