Technical Guidelines for Coolant Management in Diesel Generator Sets

1. Coolant Selection Criteria

Diesel generator cooling systems require high-quality coolant to maintain optimal thermal regulation. Clean freshwater sources such as rainwater, treated tap water, or filtered river water are recommended. Hard water (e.g., well water or groundwater) contains dissolved minerals (e.g., calcium, magnesium) that promote scale formation within engine waterways, impairing heat transfer efficiency and potentially causing overheating. If hard water must be used, implement a water softening process prior to application.

2. Pre-Operation Inspection

• Coolant Level Check: Verify coolant levels against manufacturer specifications. Top up only with the same type/brand of coolant to avoid chemical incompatibility.

• Sealing Integrity: Inspect hoses, clamps, and connections for leaks. Maintain a 5 cm gap between the coolant surface and the sealing cap to accommodate thermal expansion.

3. Coolant Refill Protocol
Due to air entrapment risks in complex cooling systems, employ a phased filling method:
a) Perform an initial fill until coolant becomes visible in the inlet pipe.
b) Allow the system to stabilize for 5–10 minutes.
c) Start the engine and run at idle for 2–3 minutes to circulate coolant.
d) Shut down the engine and let it cool for 30 minutes.
e) Recheck levels and refill incrementally until reaching the designated mark.

4. System Deaeration Procedure
Air pockets reduce cooling efficiency and may cause localized overheating. Execute bleeding as follows:

1. Remove the radiator cap (ensure the engine is cool to prevent scalding).

2. Sequentially open bleed screws starting from the lowest point in the system (e.g., engine block) and progressing upward.

3. Close each screw once a steady coolant flow without bubbles is observed.

4. If equipped with auxiliary heaters, open their valves during this process.

5. Antifreeze Solutions
For subzero environments, use ethylene glycol- or propylene glycol-based antifreeze mixed with demineralized water. Key considerations:

• Freezing Point: The coolant mixture must have a freezing point at least 5°C below the expected minimum ambient temperature.

• Concentration Ratio: Follow the antifreeze manufacturer’s dilution guidelines (typically 40–60% glycol-to-water ratio). Avoid exceeding 70% glycol, as this reduces heat capacity.

• Inhibitor Additives: Ensure antifreeze contains corrosion inhibitors compatible with aluminum, copper, and ferrous components.

6. Maintenance Best Practices

• Periodic Testing: Use refractometers or hydrometers to verify glycol concentration and pH levels (target 7.5–11).

• Coolant Replacement: Drain and replace coolant per OEM intervals (usually every 1,500–2,000 operating hours) to maintain additive effectiveness.

• Scale Prevention: In hard water regions, install inline filters or ion exchange resins to minimize mineral deposits.

7. Safety Precautions

• Never open the radiator cap when the engine is hot. Allow the system to cool below 50°C before servicing.

• Dispose of used coolant in compliance with local environmental regulations due to its toxicity.

• Wear PPE (gloves, goggles) when handling antifreeze concentrates.

Conclusion
Proper coolant management directly impacts diesel generator reliability and lifespan. Adherence to these protocols ensures efficient heat dissipation, prevents cavitation damage, and mitigates corrosion risks. Always consult the generator’s operation manual for model-specific requirements.