66 Maintenance

Maintenance Tasks and Schedule for Four Stroke Engines

Although maintenance tasks for specialized systems have been highlighted in previous chapters, this is an overview of general maintenance tasks for four stroke engines. Keeping on schedule with general maintenance will prolong the life of your equipment, and keep it working reliably and efficiently. General maintenance includes:

Oil changes

Engine oil is an essential factor in engine function. Regular oil changes keep engine components lubricated to keep things running smoothly and prevent wear. Oil changes are normally recommended every 50-100 operating hours, or annually- whichever comes first.

Air filter cleaning or replacement

Air filters are in place to keep contaminants from entering the engine and causing damage. Making sure that the air filters are clean and still filtering out all the debris will maintain engine function and fuel efficiency. It is recommended that air filters are cleaned or replaced either annually, or after every 25-50 operating hours.

Spark plug inspection or replacement

Checking spark plugs for wear, damage, or corrosion will keep the ignition system working well. Intervals of replacing spark plugs can vary, but typically every 100-300 operating hours will maintain the ignition system,

Fuel system maintenance

Using fuel that is clean and the proper kind will help maintain the fuel system. Also, inspect the fuel lines for any leaks or clogs.

Cooling system inspection

To prevent the engine from overheating, maintaining engine coolant levels is an important step in engine maintenance. Coolant replacement is normally recommended by the manufacturer, but intervals can include every two to three years.

General inspection and cleaning

Inspecting the engine for loose nuts or colts, corrosion, obvious signs of wear or damage, or leaking can help identify potential issues and keep the engine working to its peak performance.

Documentation and manufacturer’s recommended maintenance

Within the owner’s manual of the equipment, there will be manufacturer’s recommendations for maintenance and procedures. Checking the owner’s manual will ensure that you are giving the engine the specific care and inspections required. Keeping detailed records of all the maintenance done, including the dates, hours of operation, and parts replaced will help with keeping the engine servicing on schedule.

Valve Adjustment

Some four-stroke engines require periodic valve adjustments to maintain proper valve clearance and engine performance. Consult the manufacturer’s recommendations for the specific engine model regarding the frequency and procedure for valve adjustments.

Maintaining small engines: https://www.youtube.com/watch?v=YVdFIFndNoU (15 min)

Maintenance Tasks and Schedule for Two Stroke Engines

Many of the general maintenance tasks for two stroke engines are the same as four stroke engines, such as general inspection, replacing the spark plug and air filter, and maintaining the fuel system. Where it differs is when it comes to parts that are specific to two stroke engines, such as the exhaust system and crankcase oil. For the most part, two stroke engines are cooled by air, so they do not require the same maintenance on a cooling system as a four stroke engine. Like with four stroke engines, equipment using a two stroke engine will have a user’s manual with all of the manufacturer’s recommendations. Keeping up-to-date manufacturer’s recommendations and documenting all of the servicing will prolong the life of the engine.

Crankcase oil in two stroke engines is similar to engine oil in four stroke engines- it lubricates the engine components to prevent wear and damage. Some two stroke engines require regular replacement of the crankcase oil. Refer to the manufacturer’s recommendations for the specific engine model regarding the frequency of maintenance.

Check the exhaust system, including the muffler and exhaust ports, for signs of blockage, carbon buildup, or damage. Clean or replace the muffler, and remove any carbon deposits from the exhaust ports as needed to maintain engine performance.

Safety Procedures

Read the Manual: Always read and understand the manufacturer’s maintenance manual before performing any maintenance tasks. Familiarize yourself with the engine’s components, recommended procedures, and safety precautions.

Wear Personal Protective Equipment (PPE): Always wear appropriate personal protective equipment, including safety glasses or goggles, gloves, hearing protection, and protective clothing, such as coveralls or a shop apron, to prevent injury from flying debris, chemicals, or sharp objects.

Work in a Well-Ventilated Area: Perform maintenance tasks in a well-ventilated area to minimize exposure to exhaust fumes, fuel vapors, and other harmful gases. If working indoors, use exhaust ventilation or wear a respirator mask if necessary.

Turn Off the Engine: Before starting any maintenance work, ensure that the engine is turned off and the ignition key is removed to prevent accidental starts or ignition during servicing.

Allow the Engine to Cool Down: Allow the engine to cool down completely before performing maintenance tasks, especially if working on components such as the exhaust system or spark plugs, which can become extremely hot during operation.

Use Proper Tools and Equipment: Use the correct tools and equipment for the job and ensure they are in good condition. Avoid using damaged or worn-out tools, as they can increase the risk of accidents and injury.

Secure the Engine: When working on an engine, make sure it is securely mounted or supported to prevent it from falling or tipping over during maintenance tasks. Use engine stands, blocks, or other appropriate supports as needed.

Follow Proper Lifting Techniques: When lifting heavy components or parts, use proper lifting techniques to prevent back strain or injury. Bend your knees, keep your back straight, and lift with your legs rather than your back.

Avoid Smoking or Open Flames: Never smoke or use open flames near the engine or fuel system components, as they can ignite fuel vapors and lead to fire or explosion hazards.

Dispose of Waste Properly: Dispose of used oil, fuel, and other hazardous materials in accordance with local regulations and environmental guidelines. Do not dump them into drains, sewers, or the environment.

Keep Work Area Clean and Organized: Maintain a clean and organized work area to minimize the risk of slips, trips, and falls. Store tools, parts, and other materials in designated locations when not in use.

Know When to Seek Professional Help: If you encounter any problems or difficulties during maintenance tasks, or if you are unsure about how to proceed safely, seek help from a qualified mechanic or technician.

Periodic Maintenance

Many mechanical problems with a piece of equipment can be avoided by maintaining its engine.

Engine troubles can be avoided by keeping the engine clean inside and out. Dirt blocking the cooling fins and air cleaner will cause the engine to overheat, which can lead to serious damage. It is important to change a four-stroke engine’s oil periodically because combustion byproducts eventually work their way into the oil and reduce its lubricating properties. You can keep track of an engine’s operating hours by placing tape on the machine and keeping a running tally of usage. Alternatively, you can estimate the yearly usage and mark the service dates on a calendar. Equipment used seasonally, such as lawnmowers or snow blowers should be checked and cleaned at the beginning and end of each season, and again during midseason if the machine is used frequently.

• An engine that has been in storage for an extended period may be hard to start because the gasoline has evaporated from the entire fuel system
• Such an engine must be primed
• Some models have a priming button that will pump fuel into the carburetor
• On simpler models, attempting to start several times with the choke closed will draw fuel into the carburetor
• A short squirt of starting fluid into the carburetor should get a sound but reluctant engine going
• Remove the air cleaner to gain access to the carburetor
• Starting fluid is sold at auto parts stores. If an engine fires several times at full choke but will not keep running, it will probably start and run at half choke.

Intervals of maintenance

Before each use:

• clean the cooling air intake screen (usually visible at the top of the flywheel), the engine cooling fins, and the oil filler area to prevent dirt buildup
• Check the oil level on four-cycle engines. Use the dipstick if your engine has one. Otherwise, open the oil filler plug and make sure that the oil is up to the opening.
• If your electric starter uses a wet cell battery, check the fluid level in each battery cell. Charge the battery if it needs it.

Every 25 operating hours:

• change the oil in a four-stroke engine. Use a separate drain plug, if your engine has one. Otherwise, tip the machine and pour old oil out of the filler hole. Refill with the type and amount of oil listed in the manual.
• Change the oil and wash the filter on the oil bath air cleaners
• Clean or replace dry-type air filters. Check the owner’s manual for replacement intervals under various operating conditions.

Every 50 operating hours:

• Remove the spark plug. Clean it, or replace it if necessary.
• Examine the breaker points and reset the gap, or replace the points and condenser
• If the carburetor has a fuel sediment bowl, remove it, clean it, and reinstall it
• Every 150 operating hours:
• Check the ignition timing and adjust it if necessary
• Check clearance between valve stems and tappets
• Clean carbon from the cylinder head and valves. Install a new head gasket.