Northern Lights M673L2 Engine Engine

• Temperature gauge shows temperature within normal range but shutdown is activated
  Fix: Check the engine crankcase oil level. If low, fill with recommended lubricating oil and restart. Watch the oil pressure gauge carefully and shut off the engine if it does not show a normal reading (20-60 PSI) after a few seconds of operation. If the oil level is normal, DO NOT restart the engine. Call your dealer for assistance.
• Starter Inoperative
  Cause: Check DC circuit breaker, Loose or corroded connections
  Fix: If the breaker is tripped, reset it, Clean and tighten loose battery and harness plug connection
• Starter Cranks Slowly
  Cause: Low battery output, Crankcase oil too heavy
  Fix: Battery is too small, Battery cables are too small, Check specific gravity of each battery, Check electrolyte level of each battery, Fill with oil of appropriate viscosity, Clean and tighten all battery connections
• No fuel
  Fix: Check level of fuel in fuel tank
• Low Oil Pressure
  Cause: Low coolant level, Defective thermostat, Temperature gauge not working properly
  Fix: Fill crankcase to proper level, Fill tank or radiator to proper level, Check thermostats, Check water temperature with thermometer and replace gauge if necessary
• Lack of Engine Power
  Cause: Intake air restriction, Clogged primary fuel filter element, Clogged secondary fuel filter element
  Fix: Service air cleaner, Clean or replace filter element, Replace filter element
• High Oil Consumption
  Cause: Defective thermostat, Defective temperature gauge
  Fix: Remove and check thermostat, Check water temperature with thermometer and replace gauge if necessary
• High Fuel Consumption
  Cause: Injection pump out of time
  Fix: See your dealer
• Entire Electrical System Does Not Function
  Cause: Check DC circuit breaker, Faulty connection, Sulfated or worn out batteries, Improper starting procedure
  Fix: If breaker is tripped, reset it, Clean and tighten battery and harness plug connections, Check specific gravity and electrolyte level of each battery, See starting section of this manual, Take special note of Bypass Switch operation
• Engine Temperature Below Normal
  Cause: Thermostats not working properly
  Fix: Check thermostats
• Engine Runs Irregularly or Stalls Frequently
  Cause: Below normal engine temperature, Clogged primary fuel filter element, Clogged secondary fuel filter element, Water or dirt in the fuel system, Dirty or faulty injection nozzles, Air in fuel system, Improper type of fuel, Overheated engine
  Fix: Remove and check thermostat, Clean or replace filter element, Replace secondary filter element, Drain, flush, fill and bleed system, Have your dealer check injection nozzles, Inspect clamps and hoses on suction side of fuel pump for air leak, Consult fuel supplier and use proper type of fuel for operating condition, See “Engine Overheats” in next category
• Engine Overheats
  Cause: Improper valve clearance, Dirty or faulty injection nozzles, Air in fuel system, Improper type of fuel, Water or dirt in the fuel system, Clogged primary fuel filter element, Clogged secondary fuel filter element
  Fix: Reset valves, Best done by dealer, Replace injectors, Best done by dealer, See your local dealer, Service air cleaner, Clean or replace filter element, Replace secondary filter element
• Engine out of time
  Fix: See your dealer
• Engine Knocks
  Cause: Defective muffler (back pressure too high), Insufficient oil, Defective temperature gauge
  Fix: Have dealer check back pressure, Call your dealer, Check water temperature with thermometer and replace gauge if necessary
• Engine has shutdown
  Fix: Check the temperature gauge. If above 205°F (96°C) for marine units or 230°F (110°C) for industrial units, shut off the engine immediately. Use the Trouble Shooting Guide on page 24 to isolate the cause of the overheat.

Compiled from service & troubleshooting documentation across every generator set that uses the Northern Lights M673L2.

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.