Construction machinery often encounters flooding due to construction activities, accidents, or natural disasters. Operators are advised to follow the guidelines below to properly handle machinery after it has been submerged.

I. Do Not Start the Machine Prematurely

Before thoroughly inspecting a machine that has been submerged in floodwater, never attempt to start it blindly. Starting a machine without proper inspection can cause severe damage or system failure.

The main concern is not just water ingress, but also mud and debris. Mud is particularly difficult to remove — much like in flooded houses, it is often harder to deal with than the water itself.

II. Careful Handling and Inspection Before Operation

After flood exposure, machines should undergo careful cleaning and inspection before any operation. Start by manually rotating the engine at least two revolutions before attempting to start. Gradually add load once initial checks are satisfactory.

Specific steps include:

1. Drain Muddy Liquids

   • Assess the depth of water and mud ingress.

   • Do not stir up hydraulic oil, fuel, or engine oil.

   • Quickly drain all contaminated liquids from the tanks or reservoirs. Use flowing water to wash out residual sludge.

   • To check cleanliness, insert a thin, clean plastic tube to the lowest point of the tank, seal the top, then quickly remove it to see if any residual water or mud remains.

2. Electrical System Inspection

   • If the hydraulic tank, transmission, engine sump, front/rear drive axles, and wheel reducers are clean, proceed to inspect electrical systems.

   • Focus on ECUs, instrument panels, sensors, connectors, starters, and internal engine components.

   • Dry thoroughly. This step, while labor-intensive, is cheaper and often avoids part replacement.

   • If electrical components are well-sealed and show no water ingress, this step may be skipped.

3. Handling Water-Damaged Electrical Components

   • For any components that have been submerged, disconnect all connectors, clean with electronic contact cleaner, lubricate, and reinstall securely.

4. Starter and Alternator

   • Remove rust and lubricate or replace bearings if corroded.

   • Use ISO-P5 grade bearings or better for replacement (not all imported bearings meet this standard).

   • Measure coil insulation resistance before reinstalling.

5. Air Conditioning Components

   • Control boards, damper motors, and compressor clutch coils should be treated similarly.

6. Lighting Systems

   • Relatively minor and straightforward to handle compared to the above.

7. Hydraulic Systems Contaminated by Floodwater

   • Remove water using oil-water separation and filtration.

   • Do not replace hydraulic oil unless absolutely necessary; replacement is costly.

   • Untreated emulsified hydraulic oil can severely damage pumps, motors, and cylinders.

8. Engine Submerged in Floodwater

   • Focus on removing mud without major disassembly.

   • Drain water from the sump and remove sludge.

   • Remove and inspect all injectors, clean piston tops with compressed air and diesel or kerosene.

   • Manually rotate the engine at least two full turns.

   • If resistance is normal, add engine oil, use the starter to rotate, and remove any remaining debris from piston tops.

   • Reinstall inspected injectors, run at low-to-mid idle for at least 5 minutes.

   • If normal, replace engine oil and return the machine to service.

9. If Problems Persist

   • Only then should the engine be disassembled and thoroughly cleaned. Do not force operation, as this may cause greater damage.

10. Hydraulic Transmission, Torque Converters, and Axles

• Submerged components often allow water ingress via the open breather.

• Recommended: replace transmission fluid twice.

• Fluid can be reclaimed and reused after proper treatment.

I have handled multiple cases of machinery submerged in floods or sliding into reservoirs — including rollers, excavators, bulldozers, and graders — and these procedures are based on accumulated experience.