Controller displays LOW COOLANT or COOLANT LEVEL alarm and generator will not run or shuts down after a short period.

Safety first: Turn OFF the generator and disconnect the battery negative cable. Allow the engine to cool completely; never open the radiator cap on a hot engine.

Steps:

• Check coolant level: Remove the top service panel on the Gillette enclosure. Inspect the coolant recovery bottle and radiator neck (if accessible). Fill with the specified coolant mix (typically 50/50 ethylene glycol and distilled water) to the indicated level.
• Inspect for leaks: Look around radiator core, upper and lower radiator hoses, heater hoses (if equipped), water pump weep hole, and hose clamps. Tighten loose clamps and replace cracked hoses.
• Check coolant level sensor: Many Gillette liquid-cooled sets use a float or probe-type level sensor in the radiator or expansion tank. Disconnect the sensor connector, inspect for corrosion, clean with electrical contact cleaner, and reseat. If the alarm persists with correct coolant level, the sensor may be faulty.
• Bleed air: If the system was low, air pockets may form. Follow the engine manufacturer’s bleeding procedure (often involves running at idle with cap off until bubbles stop, then topping off and reinstalling the cap).
• Persistent loss of coolant: If coolant disappears with no visible leak, suspect internal issues (head gasket, EGR cooler if equipped). Contact a qualified technician.