How to Store a Diesel Generator When Not in Use

Diesel generators are reliable machines that provide backup power during outages or serve as primary energy sources in remote areas. However, there are often periods when a generator is not needed—such as between projects, during seasons of low demand, or when kept as an emergency standby. Proper storage during these idle times is essential to maintain efficiency, prevent damage, and extend the lifespan of the equipment.

Improper storage can lead to fuel degradation, corrosion, battery failure, or mechanical issues that reduce performance when you need it most. To avoid these problems, it’s important to follow best practices for storing your diesel generator.

How to Store a Diesel Generator When Not in Use

Here are the key steps to properly store your diesel generator when it’s not in use.

1. Clean the Generator Thoroughly

Before putting your generator into storage, give it a proper cleaning. Remove dirt, dust, oil residues, and debris from its surface and ventilation areas. Accumulated grime can trap moisture and lead to rust or clogged air passages. A clean generator also makes it easier to spot leaks or damage later on.

2. Drain or Stabilize the Fuel

Diesel fuel does not last indefinitely. Over time, it can degrade, form sludge, and attract microbial growth. Storing a generator with untreated fuel in the tank may cause clogs in the filters, injectors, and fuel lines.

You have two main options:

• Drain the tank completely if you expect the generator to remain unused for a long time.

• Use a fuel stabilizer if the generator will be stored for a shorter period (up to 12 months). Stabilizers prevent oxidation and microbial growth, keeping fuel fresh.

Always run the generator for a few minutes after adding stabilizer to ensure treated fuel circulates through the system.

3. Check and Change the Oil

Old oil can contain contaminants that may damage the engine when the generator is started after storage. Changing the oil and replacing the filter before storage is a smart precaution. Ensure the oil is topped up to the recommended level to provide full lubrication protection during idle periods.

4. Inspect and Maintain the Battery

Batteries are particularly vulnerable when a generator is stored. If left unattended, they may lose charge or even become damaged due to sulfation. To protect the battery:

• Disconnect it if the generator will be unused for a long time.

• Store the battery in a cool, dry place.

• Use a trickle charger to maintain optimal charge levels.

A weak or dead battery is one of the most common reasons generators fail to start after long storage.

5. Protect Against Moisture and Corrosion

Moisture is the enemy of mechanical and electrical components. Always store your diesel generator in a dry, well-ventilated area, away from direct rain, humidity, or damp floors. If outdoor storage is unavoidable, use a weatherproof generator cover, but ensure there is ventilation to prevent condensation buildup.

Spraying metal parts with a light protective oil can also help prevent corrosion.

6. Maintain the Cooling System

The cooling system should be checked and topped with the correct mixture of coolant before storage. If your generator will be exposed to freezing temperatures, make sure the coolant has sufficient antifreeze to prevent damage.

Blocked or neglected cooling systems can cause overheating when the generator is eventually used again.

7. Protect Air Intakes and Exhausts

Rodents, insects, and debris can enter through exhaust or intake openings if the generator sits idle for too long. Cover these areas with breathable materials to prevent blockages without trapping moisture.

8. Perform Regular Exercise Runs

If the generator is in long-term standby mode (e.g., emergency backup for a building), it should be run periodically—typically every 30 to 60 days—for about 30 minutes. This helps:

• Keep engine components lubricated.

• Prevent fuel system clogs.

• Recharge the battery.

• Identify potential issues before an emergency occurs.

9. Store with Documentation

Attach or store maintenance records, service logs, and operation manuals with the generator. Keeping track of when it was last serviced or exercised ensures no critical steps are missed when it is brought back into use.

10. Cover and Secure the Generator

Finally, cover the generator with a breathable, dust-resistant cover to keep out dirt and insects. Avoid fully airtight covers, as they can trap condensation. If stored outdoors, ensure the area is secure to protect against theft or vandalism.

Conclusion

Proper storage of a diesel generator is not just about putting it away until the next time it’s needed. It’s about preserving its reliability, preventing fuel and engine problems, and ensuring it’s ready to deliver power at a moment’s notice. By following steps such as cleaning, draining or stabilizing fuel, maintaining batteries, protecting against moisture, and conducting periodic exercise runs, you can extend the life of your generator and avoid costly repairs.

When stored correctly, your diesel generator will remain a dependable power solution—ready to perform whenever you need it most.