Generators are essential pieces of kit, whether they’re serving as backup power during emergencies or working as a primary power source on remote or off-grid sites. But while generators are built for durability, they’re far from maintenance-free.
Like any machine with moving parts and combustion processes, a generator needs regular attention to keep running reliably. Routine maintenance is crucial as a preventive measure against costly repairs and potential failures. Neglecting maintenance can lead to escalating issues that not only hinder the generator’s performance during emergencies but also result in a greater financial burden due to necessary repairs.
In this guide, we’ll walk through the key maintenance practices every generator owner or operator should follow.
Introduction to Generator Maintenance
Generator maintenance is crucial for ensuring the reliability and efficiency of power generators. Whether you rely on diesel generators for primary power or standby generators for backup during emergencies, regular generator maintenance is essential. By performing routine checks and adhering to a maintenance schedule, you can prevent power failures and reduce the risk of equipment damage.
A well-maintained generator provides sufficient power and operates at peak performance, reducing the need for costly repairs. Diesel generators, in particular, require regular maintenance to ensure they function correctly and provide the necessary power. Standby generators also need regular maintenance to guarantee they will work when needed, providing backup power during emergency situations.
Generator servicing is essential for extending the service life of the generator and preventing corrosion. Regular maintenance checks, such as oil and filter changes, help keep the generator in prime condition. By creating a maintenance schedule and performing regular generator maintenance, including routine checks and load testing, you can ensure your generator remains reliable and efficient.
Generator Maintenance Matters More Than You Think
It’s easy to take a generator for granted, especially if it’s only used occasionally. But just like a car that sits idle for months, a generator that isn’t regularly inspected can deteriorate quickly. To prevent common issues and ensure the generator is ready when needed, it is crucial to perform routine maintenance. This includes tasks such as changing oil and testing the battery, which can prevent malfunctions and costly repairs. When you do need it (during a storm, outage, or equipment failure) you may discover it won’t start, or worse, fails mid-operation.
Common issues from a lack of maintenance include:
- Starting problems – often due to battery failure or fuel degradation
- Fuel system blockages – from sediment, microbial growth, or water ingress
- Overheating – due to coolant issues or airflow blockages
- Excessive wear – on engine components, bearings, and belts
- Unplanned downtime and high repair costs – especially if emergency callouts are needed
Understanding Maintenance Intervals
A good maintenance strategy is structured around timeframes. Daily checks prevent minor faults from escalating, while monthly and quarterly inspections catch wear-and-tear before it causes real damage. Having your generator serviced regularly, such as every six months or after a certain number of operating hours, ensures optimal performance and reliability. Annual servicing brings everything together with a thorough assessment.
We’ve broken it down for you:
Daily Checks
These are your everyday inspections—quick, straightforward, and essential for catching early issues.
- Oil and coolant levels: Even small dips below optimal levels can trigger overheating or cause lubrication failure. Top up as needed and log any unexpected consumption.
- Leaks: Scan under and around the generator for any signs of fluid leakage. Focus on hoses, gaskets, and joints (small leaks often indicate wear or pressure problems).
- Battery terminals: Loose or corroded terminals are a common cause of failure. Gently test the cables for movement and look for corrosion buildup.
- Oil filters: Regularly inspect oil filters to ensure they are clean and functioning properly. This helps maintain the generator’s performance and longevity.
- General visual inspection: Look for frayed cables, signs of rubbing, loose bolts, or anything that appears out of place. Generators vibrate a lot, and fasteners and components can shift over time.
- Control panel review: Understand your warning lights and messages. Don’t just check that it’s ‘green’, learn to interpret subtle changes in indicators and performance.
Daily Checks of the Air Filter
Daily checks of the air filter are essential for ensuring the generator operates efficiently and effectively. A clogged air filter can reduce the generator’s performance and increase fuel consumption. Regularly cleaning or replacing the air filter can help prevent this issue and keep the generator running smoothly.
The air filter should be inspected daily, and cleaned or replaced as needed, to ensure the generator functions properly. A dirty air filter can also lead to wet stacking, which can cause damage to the generator and reduce its service life. By performing daily checks of the air filter, you can identify potential issues before they become major problems.
Regular maintenance, including daily checks of the air filter, can help extend the service life of the generator. A well-maintained air filter is essential for the generator’s peak performance and efficient operation.
Weekly Checks
Weekly checks go a bit further and involve starting the generator under real-world conditions.
- Test run under load: Don’t just switch it on, run it under at least 30% load for 30 minutes. This warms up the system properly, circulates fluids, and prevents issues like wet stacking (where unburnt fuel clogs the exhaust).
- Check for water in the fuel tank: Condensation is surprisingly common, especially in varying temperatures or humid environments. Use a dip rod or water-finding paste at the base of the tank.
- Ventilation and air intake: Clear debris and ensure unobstructed airflow. Even if filters look clean, external buildup around vents can restrict performance.
- Inspect belts: Belts should flex around 1cm when pressed firmly. Over-tightening can wear bearings; under-tensioning can lead to slippage or overheating.
- Exhaust observations: Black smoke? Likely fuel-rich combustion. Blue smoke? Possibly burning oil. Both can point to deeper mechanical issues.
- Inspect coolant mixture: Regularly check the coolant mixture levels and quality to ensure effective heat dissipation and prevent overheating. Replace the coolant mixture at recommended intervals to avoid corrosion and maintain optimal engine performance.
Weekly Inspection of the Fuel System
Weekly inspections of the fuel system are necessary to ensure the generator operates correctly and provides sufficient power. The fuel tank should be checked for any signs of corrosion or damage, and the fuel level should be monitored to prevent running out of diesel fuel. The fuel filters should be inspected and replaced as needed to prevent clogging and reduce the risk of engine damage.
Regular inspections of the fuel system can help identify potential issues before they become major problems. A well-maintained fuel system is essential for the generator’s peak performance and efficient operation. Weekly inspections of the fuel system can help extend the service life of the generator and reduce the need for costly repairs.
The fuel system should be inspected by a qualified technician to ensure it is functioning correctly and safely. Regular maintenance, including weekly inspections of the fuel system, can help keep the generator in prime condition.
Monthly Maintenance
Monthly inspections are a chance to catch issues that aren’t immediately visible, especially those related to fuel and electrical performance.
- Battery load testing: Idle voltage might look fine, but it’s the load voltage that reveals battery health. A sharp drop during startup could mean replacement is near.
- Fuel filter drainage: Sediment or water should be flushed out. In colder weather, wax crystals can form in diesel, so keep an eye out for cloudy or thick fuel.
- Coolant concentration testing: Use an antifreeze tester. Proper coolant mix protects against both extreme cold and high heat.
- Electrical terminal cleaning: Use proper contact cleaner not just a wipe. Invisible oxidation builds resistance over time, impacting performance.
- Control log analysis: Don’t clear fault logs without reading them. Look for recurring codes or performance dips that could indicate an intermittent issue.
- Filter change: Regularly change the oil and filter to ensure the generator operates efficiently and is ready for use when needed. Neglecting this can lead to longer service times and impact performance.
Monthly Maintenance Generator Servicing
Monthly maintenance generator servicing is essential for ensuring the generator operates efficiently and effectively. Regular servicing can help identify potential issues before they become major problems and reduce the need for costly repairs. The generator’s oil and filter should be changed regularly to prevent engine damage and reduce the risk of corrosion.
The coolant level should be checked and topped up as needed to prevent overheating and damage to the generator. The battery should be inspected and maintained to ensure it is functioning correctly and providing sufficient power. Monthly maintenance generator servicing can help extend the service life of the generator and keep it in prime condition.
A well-maintained generator is essential for providing sufficient power and operating at peak performance. Regular maintenance, including monthly servicing, can help reduce the risk of power failures and equipment damage.
Quarterly Maintenance
Quarterly tasks go beyond inspection:
- Oil and filter changes: Always inspect the drained oil. A milky appearance could mean coolant leakage; metal shavings suggest internal wear. Replace the oil filter to ensure optimal operation.
- Fuel filter replacement: Look for fine debris inside. Black particles may indicate injector wear; rubber flakes point to fuel line deterioration. Replace the fuel filter to prevent potential failures.
- Air filter cleaning: Tap gently to remove dust. If you must use compressed air, blow from the inside out to avoid tearing the fibres.
- Cooling system temperature check: Carefully feel hoses during operation. Uneven temperatures can point to blockages or circulation issues.
- Incremental load testing: Gradually increase the load by 25% while monitoring voltage and frequency. Instability is often the first sign of control or governor issues.
Annual Maintenance: The Full System Review
This is your major service, typically involving a professional technician and a full day’s work.
- Fuel system inspection and tank cleaning: Especially important for diesel systems. Microbial growth (the “diesel bug”) can corrode tanks and clog filters.
- Alternator inspection: Beyond voltage checks—listen for bearing wear, inspect insulation, and ensure brushes (if present) are in good condition.
- Extended load bank testing: Run under full simulated load for several hours. This tests the cooling system, voltage stability, and endurance under stress.
- Valve clearance adjustment: Required annually for many engines. Incorrect clearances can cause serious engine damage if left unchecked.
- Exhaust system integrity: Flexible joints and mounting points take a beating over time. Check for cracks, corrosion, and vibration damage.
- Avoid running without load for an extended period: Running generators without load or with low load for an extended period can lead to wet stacking, causing unburned fuel to accumulate and resulting in mechanical issues and premature engine wear.
Don’t Forget the ATS (Automatic Transfer Switch)
The generator may be perfectly fine—but if the Automatic Transfer Switch fails, none of that matters.
Regular ATS checks include:
- Weekly: indicator lights – All systems should be functioning. Missing indicators may mean bigger underlying issues.
- Monthly: transfer time testing – A slow or inconsistent switch-over can indicate control circuit problems.
- Annually: settings review – Transfer delay and retransfer settings should reflect the current load and system demands.
- Pest protection: Mice and insects love warm, dark control boxes. Make sure enclosures are sealed, clean, and inspected regularly.
- Electrical connections: Vibrations during operation can cause loose bolts and electrical connections. Routinely inspect and tighten all components to ensure optimal performance.
Building a Sustainable Maintenance Strategy
The best maintenance programmes are those that evolve with your equipment. Here are some long-term strategies to consider:
- Create a maintenance calendar: Include recurring alerts, not just logs. Ensure someone is responsible for each check.
- Track performance trends: Fuel usage spikes, voltage instability, or startup delays all offer early clues of developing issues.
- Manage fuel quality: Modern diesel degrades faster than it used to. Stabilise stored fuel and rotate stock where possible.
- Vary load conditions: Avoid running at the same output all the time. Varying the load helps clear carbon deposits and tests different system components.
- Keep spare parts in stock: For older units especially, a strategic inventory of belts, filters, fuses, and common failure items can significantly reduce downtime.
- Regular maintenance: Regular servicing is more cost effective than facing the expenses associated with major repairs or purchasing new equipment.
Key Points to Remember
By taking a proactive approach, you protect your equipment, reduce the risk of failure, and gain peace of mind knowing that power will be there when you need it. Regular maintenance is essential to keep your generator in optimal working condition, ensuring it performs reliably during emergencies.
Even if your generator only runs a few times a year, those moments are critical. With proper upkeep, it will be ready for action every time.
Powertech Generators* offers flexible maintenance packages tailored to your generator’s make, model, and usage. Whether you need a one-off inspection or full-service support across multiple sites, contact the team at +44 (0)1634 572448.*
