What’s Included in Generator Preventive Maintenance?

A comprehensive generator maintenance program typically includes:

1) Routine Visual & Safety Inspections

Technicians check for:

• Oil, coolant, and fuel leaks

• Loose belts, clamps, and connections

• Abnormal vibration or noise

• Exhaust damage or unsafe routing

• Cleanliness and ventilation around the unit

2) Engine Fluid Service

• Oil and oil filter changes (based on hours run or calendar interval)

• Coolant inspection and testing (freeze point, pH, inhibitor levels)

• Fuel system checks (filters, water separators, microbial growth prevention)

3) Battery and Charging System Testing

The battery is one of the most common reasons generators fail to start.

• Test battery voltage and load performance

• Inspect terminals for corrosion

• Verify charger and alternator output

• Check battery age and replacement schedule

4) Air Intake and Exhaust System Checks

• Inspect air filters and restriction indicators

• Check for exhaust leaks, corrosion, and backpressure issues

• Confirm rain caps, insulation, and mounts are secure

5) Electrical System and Controls

• Verify voltage regulation and frequency stability

• Inspect wiring, breakers, fuses, and grounding

• Check control panel alarms and sensor functionality

• Confirm Automatic Transfer Switch (ATS) operation (if installed)

6) Load Testing (One of the Most Important Steps)

A no-load “run test” is not enough. Proper maintenance includes:

• Load bank testing to verify performance under real operating demand

• Identifying issues like wet stacking (diesel), overheating, and weak output

• Ensuring the generator can carry the facility’s critical load

Generator Maintenance Checklist (Practical Schedule)

Here’s a simple, proven schedule used across industrial and commercial sites.

Weekly (or After Heavy Use)

• Visual inspection for leaks/damage

• Check fuel level and supply lines

• Verify battery charger status

• Confirm no active alarms

Monthly

• Start and run test (15–30 minutes)

• Check oil, coolant, and belt condition

• Inspect air intake and exhaust

• Verify ATS in “Auto” (for standby systems)

Quarterly

• Replace filters as needed (fuel/air depending on environment)

• Inspect alternator and control wiring

• Test battery under load

• Check vibration mounts, fasteners, and alignment

Semi-Annual / Annual

• Oil and filter change (or by hours run)

• Coolant testing and service as required

• Full electrical inspection and output verification

• Load bank testing (recommended at least annually)

• ATS functional test and inspection

Tip: If your generator runs frequently (prime power), service intervals should follow run hours, not just calendar time.

Common Generator Problems Maintenance Prevents

Generator won’t start

Usually caused by:

• Weak battery or corroded terminals

• Low coolant/oil shutdowns

• Fuel delivery issues or clogged filters

• Faulty sensors or control panel alarms

Generator starts but won’t carry load

Often linked to:

• Voltage regulator issues

• Alternator winding problems

• Loose electrical connections

• Dirty fuel system or restricted airflow

Diesel wet stacking

When diesel generators run too lightly loaded for too long, unburned fuel builds up in the exhaust. Maintenance programs that include proper load testing help prevent this.

Generator Maintenance Best Practices (For Long-Term Reliability)

• Keep a maintenance log: run hours, service dates, test results, alarms

• Use quality fluids and filters: correct oil grade and OEM-approved filters

• Store fuel properly: prevent water contamination and microbial growth

• Exercise under load: periodic load testing protects engine health

• Maintain the environment: keep intake vents clear and enclosure clean

• Plan for parts: belts, hoses, filters, batteries, and sensors should be staged or readily available

When to Hire a Professional Generator Maintenance Contractor

While basic inspections can be done in-house, professional service is recommended when you need:

• Load bank testing and performance verification

• ATS inspections and functional testing

• Electrical troubleshooting (voltage regulation, grounding, insulation resistance)

• Fuel polishing or contamination remediation

• Cooling system flush, coolant analysis, and leak diagnostics

• Compliance documentation for facility audits

A qualified provider can also create a site-specific preventive maintenance plan based on generator type, operating hours, and criticality of loads.

Generator Maintenance FAQs

How often should generators be serviced?
Most standby generators need routine monthly exercise and annual service, but the correct schedule depends on run hours, fuel type, and environment.

What’s the most common cause of generator failure?
Battery problems are a leading cause of no-start events, followed by fuel issues and lack of proper load testing.

Do I really need load bank testing?
If reliability matters, yes. Load testing confirms the generator can carry real demand and helps identify hidden problems before an outage.

If you want generator maintenance handled the right way—safely, thoroughly, and with documentation you can trust contact Bunney’s Inc. Our team can help you build a preventive maintenance plan, perform load bank testing, troubleshoot performance issues, and keep your generator system job-ready year-round.

Reach out to Bunney’s Inc. today to schedule service or request a maintenance assessment.

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