A standby generator differs from a working one in a way that is easy to miss: it fails not from wear, but from standing idle. The set is bought so that it starts on the one day it is needed — and that day is usually the first time anyone has looked at it in months.
The monthly test run matters more than the annual service
The single most valuable habit is a short test run once a month, and ideally under real load rather than idling. It circulates oil, keeps seals from drying out, charges the battery and — most importantly — tells you the set works while there is still time to fix it.
Running with no load is better than nothing but not equivalent: a diesel engine at low load does not reach working temperature, unburnt fuel accumulates in the exhaust, and over time this causes the wet stacking that shortens engine life. If the facility cannot spare real load, a load bank is the correct answer.
What is checked between services
- Oil level and condition — the most common cause of a failed start is not a fault but an empty or degraded sump.
- Coolant — level, and the antifreeze rating before winter.
- Battery — the classic failure point. A generator in perfect mechanical order will not start on a dead battery; a set that stands unused needs a maintenance charger.
- Fuel — diesel ages. Condensation, bacterial growth and sediment in a tank that is rarely emptied can block filters exactly when the set is needed.
- Air filter and radiator — dust, poplar fluff and leaves choke cooling; a set in a plant room accumulates them more slowly but still accumulates them.
- Leaks and connections — oil, fuel and coolant traces on the frame are an early warning, not cosmetic.
Servicing by hours and by calendar — whichever comes first
Manufacturers specify intervals in running hours, but a standby set rarely accumulates them. This is why the calendar rule exists in parallel: even a generator that has run almost nothing needs oil, filter and coolant attention on schedule, because oil degrades with time and not only with use.
The practical rule: follow the manual for your specific engine, apply whichever limit arrives first, and keep the harsher figure in dusty or hot conditions.
Keep a logbook — it is what makes a claim work
Every run, every service and every part replaced belongs in a record. Two reasons. First, it shows a trend: oil consumption creeping up or start time lengthening is visible in a log and invisible in memory. Second, a warranty claim on a set with no service history is a difficult conversation, and the manufacturer is within their rights.
What usually goes wrong at the worst moment
In practice the causes of a failed start are dull and repetitive: a flat battery, stale fuel, a clogged filter, no oil, an automatic transfer switch that was never tested after installation. Almost none of it is expensive to prevent — it simply requires that someone is responsible for it.
We supply and service the generating sets we deliver, including sites where a failure is not an inconvenience: 26 generators of 120 kW for humanitarian operations and 35 sets securing railway stations. If you have a generator on site and no one currently maintaining it, tell us the model and location — we will propose a schedule.