Why generators show "engine overheats": 72 documented causes and brand-specific fixes, compiled across 31 manufacturers.
Improper lubrication. Poor ventilation. Dirty or oily cooling surfaces. Retarded ignition timing. Generator overloaded.
3 brands- Cummins/Onan: Provide ample ventilation at all times. Keep the engine clean. Retime ignition. Reduce load.
- Garretson: See Low Oil Pressure. Provide ample ventilation at all times. Keep the engine clean. Retime ignition. Reduce load.
- NEC: See Low Oil Pressure. Provide ample ventilation at all times. Keep the engine clean. Retime ignition. Reduce load.
(1) Carburetor choke valve partially closed. See that choke is wide open (par. 16?i). (2) Insufficient lubrication. Fill crankcasc to proper level (par. 56).
2 brandsCoolant level low, Cooling system clogged, Fan v-belte slipping, Exhaust system clogged
2 brands- EMC: .Add water to radiator (par. 47). -Service cooling system (par. 47). -Adjust v-belts (par. 48). -Remove restriction.
- Libby Welding: .Add water to radiator (par. 47). -Service cooling system (par. 47). -Adjust v-belts (par. 48). -Remove restriction.
Coolant level is low or coolant is contaminated
2 brands- Gas-KOHLER: Check and refill coolant if necessary. Refer to the 'Cooling System' section for details.
- Kohler: Check and refill coolant if necessary. Refer to the 'Cooling System' section for details.
Improper lubrication. Poor ventilation, Dirty or oily cooling surfaces. Retarded ignition timing, Generator overloaded.
2 brands- Cummins/Onan: Provide ample ventilation at all times. Keep the engine clean, Retime ignition. Reduce load.
- Onan Electric: Provide ample ventilation at all times. Keep the engine clean, Retime ignition. Reduce load.
Improper lubrication. Spar ventilation. Dirty or oily cooling surfaces. Retarded ignition timing. Generator overloaded.
2 brands- Cummins/Onan: See Low Oil Pressure. Provide ample ventilation at all times. Keep the engine clean. Retime ignition. Reduce load.
- Prestolite: See Low Oil Pressure. Provide ample ventilation at all times. Keep the engine clean. Retime ignition. Reduce load.
Restricted airflow due to dirt or debris blocking air inlet or outlet
2 brands- Bgm/Nhm: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
- Marquis: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
Dirt or oil covering engine cooling fins
2 brands- Bgm/Nhm: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
- Marquis: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
Lean fuel mixture due to: a. incorrectly adjusted fuel mixture screws. b. incorrect float level. c. dirt in carburetor. d. vacuum leak
2 brands- Bgm/Nhm: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
- Marquis: 1. Clear away any debris that may restrict airflow to set. Do not use compartment for storage area. 2. Clean away all dirt and oil from engine cooling fins. 3a. Adjust carburetor main and idle adjustment screws. 3b. Adjust carburetor float level. c. Disassemble carburetor and clean all internal passages. Replace fuel filter. d. Repair vacuum leak.
Lack of coolant in cooling system, Radiator core and/or side screens dirty, Engine overloaded, Too low crankcase oil level, Loose or defective fan belt, Defective thermostat(s), Damaged cylinder head gasket, Defective coolant pump, Defective radiator cap
2 brands- John Deere: Fill cooling system to proper level., Clean radiator as required., Reduce engine load., Fill crankcase to proper oil level., Replace fan belt as required. Check belt tensioner. (See Lubrication and Maintenance 500 Hour/12 Month section.), Test thermostat opening temperature; replace thermostats as required. (See Service as Required section.), Replace cylinder head gasket. See your John Deere engine distributor or servicing dealer., Replace coolant pump. See your John Deere engine distributor or servicing dealer., Replace radiator cap as required.
- Katolight: Fill cooling system to proper level., Clean radiator as required., Reduce engine load., Fill crankcase to proper oil level., Replace fan belt as required. Check belt tensioner. (See Lubrication and Maintenance 500 Hour/12 Month section.), Test thermostat opening temperature; replace thermostats as required. (See Service as Required section.), Replace cylinder head gasket. See your John Deere engine distributor or servicing dealer., Replace coolant pump. See your John Deere engine distributor or servicing dealer., Replace radiator cap as required.
Incorrect grade of fuel
2 brands- Atlas Copco: Use correct grade of fuel
- John Deere: Use correct grade of fuel
Coolant level is low, thermostat is faulty, radiator fins are dirty
1 brand- Kohler: Add coolant to recommended level. Replace thermostat if it is faulty. Clean radiator fins.
Engine overloaded Low coolant level Keel cooling tubes (marine sets) have been painted Cooling system needs flushing Defective thermostat Defective temperature gauge Water pump impeller worn or broken
1 brand- Northern Lights: Reduce the electrical load. Fill tank or radiator to proper level. Check hoses for loose connections and leaks. Remove paint from tubes. Flush cooling system. Remove and check thermostat. Check water temperature with thermometer and replace gauge if necessary. Check the impeller and replace if necessary.
Engine overloaded
1 brand- Northern Lights: Reduce the electrical load.
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
1 brand- Northern Lights: 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