D4/D6

Common issues

• Fuel system contamination/clogging (injectors, filters) leading to poor performance or misfires.
• Cooling system inefficiencies: Heat exchanger fouling (raw water side), raw water pump impeller wear, or thermostat malfunction.
• EVC (Electronic Vessel Control) system faults: Sensor failures (temperature, pressure, RPM), wiring corrosion, or software glitches causing erratic behavior or shutdowns.
• Turbocharger bearing wear or impeller damage due to lack of lubrication, foreign object ingress, or prolonged high-load operation.
• Belt degradation (alternator, raw water pump) leading to loss of charging or cooling.
• Corrosion of raw water system components, exhaust manifold, and electrical connections, especially in saltwater environments.
• Oil leaks from seals (crankshaft, oil pan) or filter housings due to age or improper installation.
• Engine mount degradation causing excessive vibration and potential alignment issues.

Inspection checklist

• Engine oil level and condition (color, smell, presence of water/fuel).
• Coolant level and condition in expansion tank, check for leaks around hoses and connections.
• Fuel system integrity: Inspect all fuel lines, filters, and high-pressure components for leaks or signs of weeping.
• Drive belt (alternator, raw water pump) condition (cracks, fraying) and tension.
• Exhaust system: Check for leaks, corrosion, proper insulation, and secure mounting.
• Raw water pump: Inspect for leaks, and if possible, check impeller condition (visual or by pressure drop).
• Electrical connections: Verify tightness, absence of corrosion, and proper routing/chafing protection, especially for EVC sensors.
• Engine mounts: Inspect for cracks, excessive compression, oil contamination, and secure fastening.
• Turbocharger: Listen for unusual noises (whining, grinding), check for oil leaks, and inspect for excessive shaft play (if accessible).
• Operational check: Start engine, observe for abnormal noises, vibrations, exhaust smoke, proper gauge readings (oil pressure, temp, voltage), and test emergency stop functionality.

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Engine Oil Filters (primary & secondary)
• Fuel Filters (primary & secondary)
• Raw Water Pump Impeller Kit (with gasket)
• Drive Belts (alternator, raw water pump)
• Assorted Fuses (common ratings)
• Engine Oil (sufficient for a top-up or small change)
• Coolant (pre-mixed, compatible type)
• Common Sensors (e.g., oil pressure, coolant temperature - if readily replaceable without special tools)

Safety

• Hot Surfaces: Exhaust manifold, turbocharger, and engine block pose severe burn risks.
• Rotating Machinery: Belts, pulleys, and flywheel present entanglement hazards.
• High-Pressure Fuel System: Leaks can lead to fire or explosion; exercise extreme caution during inspection/maintenance.
• Electrical Hazards: Live circuits, battery terminals, and faulty wiring can cause electric shock.
• Exhaust Gases: Risk of carbon monoxide poisoning in enclosed spaces; ensure proper ventilation and exhaust system integrity.
• Emergency Stop Functionality: Must be fully operational and regularly tested to prevent runaway engine or immediate shutdown in emergencies.

Class survey

A Class Surveyor will typically focus on: 1. **Documentation**: Verification of maintenance records, engine logbook, service history, and compliance with manufacturer's recommendations and class requirements. 2. **Operational Test**: Start and run the engine, observing for abnormal noises, vibrations, exhaust smoke, and proper operation of gauges (oil pressure, temperature, RPM, voltage). Emergency stop functionality must be tested. 3. **Safety Devices**: Functionality check of overspeed trip, low oil pressure alarm/shutdown, and high coolant temperature alarm/shutdown. 4. **Fuel System**: Inspection of fuel lines, filters, pumps, and tanks for leaks, corrosion, and proper securing. Verification of fire valves operation. 5. **Lubrication System**: Check oil levels, pressure, and inspect for leaks. 6. **Cooling System**: Inspection of raw water and fresh water circuits for leaks, corrosion, and proper flow. Heat exchanger condition. 7. **Exhaust System**: Inspection for leaks, corrosion, proper insulation, and secure mounting. 8. **Electrical System**: Check battery condition, charging system, wiring integrity, and control panel functionality. 9. **Engine Mounts & Foundation**: Inspection for integrity, signs of degradation, and proper securing to the vessel's structure. 10. **General Condition**: Overall cleanliness, absence of excessive oil/fuel accumulation, and accessibility for maintenance.