Checking to make sure all bolts are tight can prevent vibration and damage to a machine's engine. Photos: Robin Subaru
Spark plugs should be inspected after every 50 hours of engine use; plugs with cracked porcelain should be replaced immediately.

Every piece of equipment in a fleet is designed for a different purpose, and the equipment comes in a variety of shapes and sizes. However, most have one requirement in common: the use of an engine to be effective. Although the engine is usually relatively small, it plays a significant part in equipment life, performance, and quality. Because of this, it is important to pay special attention to maintaining the engine.

An effective maintenance program is the result of several different factors such as the type of equipment, the machine's work environment, and the manufacturer's specific requirements. Although there may be a few differences in how various engines are maintained, there are some basic maintenance steps that should be taken with almost any engine.

Although often overlooked, daily maintenance is usually easy and quick to perform. Attending to basic maintenance items (such as checking the oil, inspecting the air filter, and cleaning the engine) is a simple, easy way to increase engine life and performance.

Perhaps the most routine daily maintenance step is checking the oil. An insufficient amount of oil can cause serious problems and shorten the life of an engine. If the oil level is below what is recommended by the manufacturer, oil should be added until the specified level is reached. Although many manufacturers claim air-cooled engines do not use oil, heat created by the engine and working environment may cause the engine to burn a small amount; therefore, it is equally important to check the oil on air-cooled engines.

Another important practice that can prevent significant damage is checking the air filter. A clogged or damaged filter can lead to a loss in power and shorten the life of an engine by allowing dust and dirt into sensitive areas. Consult the owner's manual for instructions on how to clean a dirty filter. If a filter is damaged or so clogged that dirt cannot be removed with suggested cleaning methods, it should be replaced immediately.

One of the most basic daily maintenance steps is cleaning the engine. Cleaning gets rid of potentially harmful dust and dirt, and it also enables the operator to check the engine for leaks, loose parts, and damaged components. Damaged items should be replaced, and loose parts should be tightened. Loose parts are prone to increased vibration, which can cause damage and harm nearby components.

Particular attention should be given to any signs of fuel leakage. If a fuel leak is detected, the parts causing the leak should be tightened or replaced immediately. Failing to fix the leak is not only wasteful and inefficient, but also potentially dangerous.


In addition to daily maintenance, engines require a variety of maintenance on a less frequent basis. Engines require weekly, monthly, biannual, and annual maintenance to retain performance and extend their life. Although maintenance on all small engines follows a similar timeline, consult the operator's manuals for maintenance requirements specific to the equipment.

One item that needs to be addressed daily and bimonthly is the engine oil. The oil should be changed every 100 hours to remove potentially harmful sludge. The only exception to changing the oil after 100 hours comes when the engine is first purchased; engine oil should be changed after the first 20 hours of use to remove assembly lube and any metallic particles left from production and deposited during initial operation.

The air filter is another item that needs attention daily and bimonthly. Regardless of how dirty the air filter is, it should be cleaned every 100 hours. Additionally, the air filter should be changed on a monthly basis. If the air filter is not cleaned and changed, it is prone to clogging, which causes a loss of power and shortens engine life by allowing dirt to enter internal components.

Also, every 50 hours, an operator should inspect the spark plugs for damage, dirt, and excessive carbon buildup. Dirty spark plugs can cause a decrease in power and poor starting performance. Spark plugs with cracked porcelain should be replaced immediately, and a spark plug with a considerable amount of dirt or carbon buildup should be cleaned. An operator can use a wire brush to clean the spark plug.

It is important to clean and inspect the fuel strainer and fuel filter every month. Contaminated fuel can lead to trouble starting the engine, and because replacing the fuel line and carburetor can be expensive, it is essential to prevent unnecessary damage caused by contaminated fuel.

On an annual basis, an engine should be thoroughly inspected for dirty, broken, and misaligned parts. These faulty parts can cause a variety of engine problems, and thoroughly inspecting the engine gives the most comprehensive view of what needs to be cleaned and repaired.

Additionally, the fuel hose should be replaced annually. This reduces the chances of fuel leaks, which are uneconomical and dangerous to the operator.

Whether preparing an engine for storage or merely readying it for a typical day on the job, following appropriate maintenance recommendations will ensure a long engine life and preserve its power and performance. Although a strict schedule may appear time-consuming, most steps are fairly quick and easy to perform. And, in relation to the amount of time and money required to fix or replace a faulty engine, a few minutes spent on maintenance is a small investment to make.

— Dale Gabrielse is training manager for Robin Subaru, Wood Dale, Ill.

Suiting up for storage

In addition to a regular maintenance routine, some circumstances require special care. Many contractors live in areas where the weather prevents them from working year-round. During the off season, equipment will go for long periods without being used, and damage can occur to engines that are not properly stored. If an engine will be stored for more than 30 days, special steps need to be taken to protect it.

  • Perform all suggested daily maintenance. This includes cleaning the engine and checking the air filter. After these steps, the fuel should be drained from the fuel tank and carburetor float chamber. This is one of the most important steps in preparing an engine for storage. Over time, the volatile components of fuel evaporate and the fuel becomes stale. Stale fuel makes starting the engine difficult, if not impossible, when the machine is taken out of storage. Although it is usually suggested to drain the fuel, filling the tank with new fuel and adding a fuel stabilizer is another option for preventing stale fuel.
  • Remove the spark plug. Then, inject a few drops of oil through the spark-plug hole. This helps prevent corrosion in the cylinder bore during storage. The recoil starter knob should be pulled gently two or three times before the spark plug is placed back in the spark-plug hole.
  • Pull the recoil starter knob until you feel resistance and leave it in that position. The engine should be cleaned, and a protective cover should be placed over the unit. It is also important to make sure that a pressure washer is not used to clean the engine and that the engine is stored in a dry place.