From 2025 to 2026, major generator manufacturers have updated their maintenance manuals, specifying that three core filter parts must be replaced once a diesel generator set accumulates 500 operating hours, along with engine oil. The three components are the oil filter, fuel filter and air filter.

Industry Specifications

Huaquan Group (March 31, 2026)

Complete maintenance every 500 operating hours or every six months: replace engine oil, oil filter and fuel filter; clean or replace the air filter. The air filter needs earlier replacement (every 250 hours) in dusty working conditions.

Chongkang Power (September 5, 2025)

Primary maintenance (50–100 operating hours): replace engine oil and oil filter.

Secondary maintenance (500 operating hours): fully replace the three filters, and inspect fuel injectors and valve lash.

Ohtsuka Power (October 22, 2025)

The three filters shall be replaced every 500 hours under normal working conditions. If using poor-quality diesel fuel, replace the fuel filter every 200 hours. For units running under high temperature and heavy load, shorten the replacement cycle of the oil filter to 150–200 hours.

Shenzhen Stanford Power (October 30, 2025)

The 500-hour mark is a key deep maintenance interval. The core work includes replacing the three filters and engine oil, cleaning the fuel system and testing coolant.

Why Replace the Three Filters Timely?

Oil Filter

Its filtering capacity drops by over 70% after 500 hours of operation. Clogging caused by metal debris and carbon deposits will lead to low oil pressure, cylinder scuffing and bearing burnout. It must be replaced together with engine oil.

Fuel Filter

Built-up impurities will block the filter, resulting in hard starting, reduced power and black exhaust smoke. Excessive moisture will also corrode high-pressure oil pumps and fuel injectors.

Air Filter

Dust accumulation clogs the filter and restricts air intake, which raises fuel consumption, cuts power and causes abnormal wear of cylinder liners and piston rings.

Safety Incident Alerts

November 2025, a factory in Guangdong: The generator ran for 620 hours without filter replacement. A clogged oil filter cut off oil supply and locked the crankshaft, costing over 80,000 yuan in repairs.

January 2026, a data center in Jiangsu: Overdue fuel filter damaged the high-pressure oil pump and caused an unexpected shutdown, leading to server outage and a loss of about 200,000 yuan.

August 2025, a construction site in Sichuan: Long-term use of a dirty air filter allowed dust into cylinders, wearing piston rings severely, producing blue smoke and increasing fuel consumption by 30%.

Standard Replacement Procedures

Shut down the unit and let it idle for 3 to 5 minutes until the oil temperature drops below 60℃ before maintenance.

Replacement order: oil filter → fuel filter → air filter.

Drain old engine oil while the unit is still warm. Coat the seal ring of the new filter with a thin layer of engine oil, then tighten it manually.

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