Extended periods of idle time (especially without proper sealing and maintenance) can lead to a range of problems, severely impacting performance and reliability, and even causing permanent damage. The following are common issues:
1. Oil Deterioration and Contamination:
Oil Oxidation and Acidification: Prolonged exposure to air causes oil to oxidize, change viscosity, and generate acidic substances. These acids can corrode precision components within the engine (such as bearings, bushings, and cylinder liners), leading to increased wear during startup and even cylinder seizure.
Diesel Deterioration:
Colloid and Sedimentation: Unstable components in diesel can oxidize to form gum and sludge, clogging fuel filters, injectors, and fuel lines.
Microbial Growth: Condensation in the fuel tank is a breeding ground for microorganisms (bacteria and fungi). The mycelium (viscous substance) they form can severely clog filters and fuel lines, and the acidic metabolites they produce can corrode the metal in the fuel tank and piping. Increased Water Content: Temperature fluctuations between day and night in the fuel tank can generate condensation, leading to excessive water content in the diesel fuel, affecting combustion efficiency, exacerbating corrosion in the injection system (especially in modern high-pressure common rail systems), and even causing "rusty water" (staining).
Coolant Deterioration: The preservatives in the antifreeze gradually lose their ability to protect the metal components of the cooling system, leading to corrosion and scaling of cylinder liners, water pumps, radiator lines, and other components.
Lubricant (Grease) Drying: The lubricant (Grease) on the surfaces of bearings, gears, and other components can dry out, harden, or run off over time, losing its lubricating properties and causing dry friction damage during restart.
2. Metal Component Corrosion and Seizing:
Cylinder Liner and Piston Ring Rust: After the engine is shut down, moisture condenses in the cylinder. Unburned sulfur compounds react with water to form acid, causing rust on the inner wall of the cylinder liner and piston rings. In severe cases, the piston rings may rust into the ring grooves or become stuck to the cylinder liner (commonly known as "cylinder seizure"). Bearing and journal corrosion: When the lubricating oil film is lost or deteriorates, the bearing surfaces (crankshaft, camshaft, and connecting rod bearings) and journals are exposed to air and moisture, causing rust. This can lead to severe wear and even shaft seizure during startup.
Injector needle valve sticking: Gum or microbial blockages caused by low-quality diesel, as well as trace rust on the surface of the needle valve assembly, can cause the injector needle to stick, preventing proper injection.
Valve sticking: Drying or rusting of the lubricating oil on the valve stem and guide can cause the valve to stick, preventing it from opening or closing properly.
3. Electrical system aging and failure:
Battery damage: This is the most common problem. The battery will self-discharge even when disconnected. Prolonged lack of charging can cause:
Deep discharge: Low voltage causes sulfation of the plates, forming hard lead sulfate crystals that prevent normal charging and discharging, resulting in permanent capacity loss and even failure.
Electrolyte stratification/drying: Uneven electrolyte concentration or water evaporation can affect performance and battery life. Oxidative Corrosion of Connecting Terminals: Cable terminals and terminal posts (especially battery terminals) exposed to air will oxidize and produce white or green corrosion products (verdigris), increasing contact resistance, heat generation, and even electrical incompatibility.
Insulation Aging: The insulation materials of generator windings and control circuits may age rapidly and become brittle in hot and humid environments, reducing insulation performance and increasing the risk of short circuits.
Controller/Instrument Failure: Moisture, dust accumulation, or capacitor aging of electronic components may cause malfunction or failure of control modules (ECUs/controllers) and instruments.
4. Aging and Failure of Rubber and Seals:
Aging of Oil Seals, O-Rings, and Water Pipes: Rubber components can harden, lose elasticity, shrink, or crack due to prolonged disuse, leading to oil and water leakage after startup. Aging increases the risk of rupture in fuel and cooling water lines.
Turbocharger Oil Seal Failure: If the floating bearing oil seal of a turbocharger is not lubricated for an extended period, the rubber may deform and fail, causing oil to leak into the intake or exhaust pipes.
5. Seizing of Moving Parts:
Generator Bearing Seizure: If the grease in the generator bearings dries out or deteriorates, the bearings may become sluggish or completely stuck.
Starter Motor/Gear Seizure: The starter motor's drive gears, overrunning clutch, or internal mechanisms may seize due to dust, minor rust, or poor lubrication.
6. Intake/Exhaust System Blockage and Corrosion:
Intake System: The air filter may become clogged due to moisture, dust accumulation, or a nesting ground for rodents and insects. The intake duct may contain foreign objects or dead animals.
Exhaust System: Condensation accumulation inside the exhaust pipe and muffler can cause severe rust and perforation; exhaust valves and turbocharger blades may also rust.
Summary: Long-term storage is extremely harmful to diesel generator sets. The principle of "use it or lose it" is particularly evident here. Failure to properly seal and perform regular maintenance is equivalent to allowing the unit to become scrapped.
