Staying Out of Engine Trouble
Most people know that engines will require daily and periodic maintenance, but it’s also important to be aware of the audible and visual signs of unexpected maintenance needs. Operators should also take into consideration working conditions and how they affect engine performance. Proper engine storage shouldn’t be overlooked either.

Addressing the small issues early on, making appropriate environmental adjustments and following storage guidelines will all help prevent engine troubles from creeping up in the future.


If an engine is experiencing hard starts, the valve clearance on the intake and exhaust valves should be checked and adjusted according to manufacturer specifications. When checking the valve clearance, position the piston at the top dead center of the compression stroke and ensure the engine is cold. After the clearance is adjusted, rotate the crankshaft and check the valve clearance again.

A reduction in power often is an indication that the cylinder head and carburetor need to be inspected and cleaned. Check the cylinder head’s valves, seats, ports and guides and remove any carbon or gum deposits from the components. Check the air filter as well.

If the recoil rope hangs loose and doesn’t completely return, it could be a sign that water has intruded the engine. This indicates the lubricant may have been washed off. Remove the recoil return and apply additional lubrication to fix the problem. Ignoring the issue can result in a broken rope or eventual damage to the recoil starter.

Additionally, a loss of power or a smoking engine may signal an internal engine problem. Blue-colored smoke indicates that the engine is using oil, a problem that tends to be more common on cold days. Look to see if the breather hoses are plugged and check the piston rings, which may be bad, to determine the cause of the smoke.

If the smoke is black in color, it typically indicates that the mixture is too rich. Incorrect mixtures of air and fuel cause the majority of carburetor problems; therefore, it is important to prevent clogged jets, air passages and fuel passages that keep air and fuel from flowing freely. Check the carburetor for dirty or defective parts and clean or replace them if needed. A change in elevation also may cause black smoke, in which case the engine should be modified to handle the difference. If basic troubleshooting maintenance techniques fail to work, have a trained mechanic conduct a leakdown test or compression test to determine the cause for any smoking or power reduction.

Like smoke colors, different noises also can indicate specific problems. For instance, if the engine begins to make a popping noise or backfire, the mixture of fuel and air is likely too lean in the carburetor. A knocking noise will generally indicate a worn connecting rod, while a tinny or metallic sound may mean something is loose.

Adjusting for the Environment

In addition to a regular maintenance routine, some application circumstances require special care, such as high altitudes, heat and cold.

Altitudes above 5,000 feet may cause engines to start hard and perform poorly. Emissions also are typically higher, and operators may experience trouble with spark plugs. Modifying the carburetor will improve both performance and emission levels. Moving to a job site below 5,000 feet requires converting the engine back to levels recommended by the manufacturer. Failure to do so will cause the engine to overheat and can result in damage.

Operating an engine after the mercury has surpassed 100 degrees Fahrenheit also can be problematic. Ensuring dirt does not obstruct an engine’s cooling mechanisms will help prevent problems with overheating. However, do not attempt to cool a hot engine with water since the temperature difference will likely damage the engine.

Operators also should check and change the oil and oil filter more frequently than normal when using an engine in hot weather. Take the heat into account when choosing the oil’s viscosity, as well.

On the other end of the thermometer, monitoring the oil’s viscosity remains important. If a cold front should move in before the oil has been changed to a more appropriate viscosity, move the machine to a warm, well-ventilated space before attempting to start the engine or change the oil.

Keeping the fuel tank full will prevent moisture from condensing inside the tank when it’s cold, which can cause problems with engine operation. Ensuring the battery remains well-charged also will combat problems an operator may face in a cold environment.

One trick to ease frustration if the machine needs to remain outside and an ice storm is anticipated is to push the throttle to the middle of its speed range. Should ice form on the linkage, it will be easier to start the engine with the throttle in this position.

Suiting Up for Storage

Whether it’s the off-season or other circumstances prevent operating your engine-powered equipment for more than 30 days, special steps need to be taken to protect the engine.

The first step in preparing an engine for storage is performing all of the suggested daily maintenance items, such as cleaning the engine and checking the air filter. Next, drain the fuel 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 a stale situation.

To prevent corrosion in the cylinder bore during storage, remove the spark plug and inject a few drops of oil through the spark plug hole.  Gently pull the recoil starter knob two or three times before the spark plug is placed back in the spark plug hole. Additionally, pull the recoil starter knob until the resistance is felt, and leave it in that position. End the process with a final engine cleaning before placing a protective cover over the unit and storing it in a dry place.

When returning the engine to service, ensure the oil viscosity is adequate for the temperatures expected. Check the fuel lines and filter, making sure they are still secure and have not cracked. Be sure that the throttle, choke and governor linkages move freely before starting the engine.

The initial start for an engine coming out of storage may be slow and there could be smoke for a few minutes until any oil in the cylinder burns off. If the engine fails to start, check the spark plug since it may have been fouled by the oil added to the cylinder before the machine was stored. Clean or replace the spark plug before attempting to start the engine again.

Whether you’re preparing an engine for storage, adapting it to the weather or just keeping an eye out for warning signs, giving an engine the attention it deserves will go a long way toward keeping it out of trouble.
> Back to Top
Featured Videos
One Two Three Four

Top Stories: