Power Saver: Enjoy these Spring Tune-up Tips for Portable Generators


Maintenance not only protects mobile generators from damage and repairs. It also extends the life of the equipment, which contributes to lower ownership costs.

Maintenance not only protects mobile generators from damage and repairs. It also extends the life of the equipment, which contributes to lower ownership costs.

Many people in the United States can attest that there are really only two seasons: winter and construction. As the wintry months come to an end, fleets of mobile generators are coming out of storage in preparation for construction season. Maintenance should be a top priority to avoid costly repairs in the future. Mobile generators come in different sizes and are powered using different fuel types: diesel and liquid petroleum gas (LPG) as well as wellhead and natural gas. These engines should be treated differently with regard to maintenance and repair needs, but as a general rule they should be run biweekly to ensure — in the case of diesel — that the fuel is being used before it degrades and also to keep the engine parts lubricated.

“It’s important to maintain your generator fleet consistently to keep the engines and parts operating smoothly,” says Paul Cannestra, vice president, service operations for Generac Mobile Products. “Periodic load bank runs can go a long way toward revealing issues prior to fielding equipment and — in the case of diesel engines — prevent wet stacking and clogging of emissions components. Because of the many variables among engine sizes and fuel types, most generator manufacturers will include maintenance schedules that are specific to each generator in the operating manual. Generac even has a parts and services landing page on its website [generacmobileproducts.com/parts-service] full of resources on servicing and maintaining your mobile generator.”

Dealing with Diesel

Maintaining a diesel engine starts with daily inspections of the fuel system, including fuel filters and lines. Diesel fuel is subject to degradation and contamination over time. Water from condensation can build up within the fuel, bacteria can grow within the tank and debris from the fuel tank itself can contaminate the fuel.

“Clean, quality fuel is critical for reliable operation of a diesel generator set,” Cannestra says. “All fuels naturally absorb moisture from the air. Using a diesel fuel polisher will prevent algae growth, and keeping the tank full will reduce the amount of condensation that can form. Periodically draining the tank and replenishing it with fresh fuel can help flush out old expired fuel and contaminants.”

Because many Tier 2- and Tier 3-compliant engines have aftermarket solutions applied to upgrade them to Tier 4 standards, it is also important to understand how those components affect routine maintenance. Any other maintenance differences with regard to the tier with which the engine complies will be clearly outlined in the generators’ operations manuals. It’s always helpful to keep a library of operations manuals for all generator equipment readily accessible and up to date.

Additional maintenance on a diesel engine should include regular oil changes as recommended by the manufacturer. For that reason, keeping an accurate log of all maintenance performed is good practice. Schedules for more comprehensive maintenance requirements, such as draining or replacing fuel filters as well as unit performance tests, are specified by each generator’s manufacturer in the operations manual.

Natural Gas Necessities

Natural gas generators feature engines typically based upon a diesel engine block. Because natural gas combusts at a higher temperature than diesel and doesn’t provide the lubrication benefits of diesel, the more robust diesel engine block is required instead of one used for similar spark-ignited applications, such as a gasoline engine block.

“The major differences between a gaseous-fueled engine and a diesel engine are the ignition system and oil type,” Cannestra says. “These differences mean that the maintenance requirements are slightly different from that of a diesel engine.”

The ignition system in a natural gas engine includes spark plugs, which must be inspected and changed at intervals specific to the generator. These intervals depend on the size of a generator’s engine and the generator’s load capacity. For example, a 150-kW gen set might require an oil change at every 750 hours, while a larger 350-kW unit might have a recommended oil change interval of 250 hours.

It’s important to consult the manufacturer’s operations manual for the proper interval between oil changes and adjust for the extreme working environments in which mobile equipment frequently operates. These gen sets also require a different oil type. The oil used in a natural gas unit should have little to no sulfur or ash and no detergents, so it is very important not to confuse it with diesel engine oil.

Other General Maintenance

One of the most important ways to ensure reliable mobile generator operation over time, regardless of fuel type, is to keep it clean. “A clean gen set helps prevent rust, keeps electrical outlets and connections free of debris and ensures effective engine cooling,” Cannestra says. “Because these units tend to be used in dirty environments, it’s important to take time every now and then to clean them up.”

Periodically inspecting the trailer bed, including the tires, ensures there is no damage that would lead to a failure during transport. Make sure the hitch is in good working order, as well. Two other components that should be inspected regularly are the fan belt and the battery. Ensure the fan belt is not loose and does not have any holes or tears. As for the battery, check for corrosion around the battery terminals and look for any indications that the battery might be leaking.


Maintenance not only protects mobile generators from damage and repairs, it also extends the life of the equipment, which contributes to lower ownership costs. Those experienced in servicing and maintaining diesel or spark-ignited engines can likely perform much of the routine maintenance themselves. However, the manufacturer or their licensed dealers will also have a team of trained service technicians available to perform regular maintenance checks.

“The most important thing you can do for your generator is to properly maintain it on a strict schedule,” Cannestra says. “These units are investments, and to get the biggest return, you have to regularly put the effort into keeping them in top shape.”

Donna McGinnis is the marketing manager for Generac Mobile Products.

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