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Low coolant level

Why generators show "low coolant level": 3 documented causes and brand-specific fixes, compiled across 9 manufacturers.

Replenish

1 brand
  • Airman: Call your nearest dealer

Shutdown, Low coolant level, Coolant hoses leaking, Engine block or water pump leaking

1 brand
  • Generac: Allow engine to cool, then check coolant level in radiator. Add coolant, if needed.

Possible Causes: Excessive liner standout. Excessive liner standout differential between cylinders. Low head bolt clamping loads. Out-of-flat/damaged/rough block surface. Out-of-flat/damaged/rough cylinder head surface. Oil or coolant overheating. Cracks/creases in gasket body surfaces. Damage/voids in elastomer beading.

1 brand

Affected models

Atlas Copco QAS 108Cummins/Onan 100GGHHCummins/Onan 1100DFLBCummins/Onan 1120 DFLCCummins/Onan 1250DFLCCummins/Onan 125GGHJCummins/Onan 1290DFLECummins/Onan 1500DFLECummins/Onan 55GGHFCummins/Onan 60GGHECummins/Onan 60GGHFCummins/Onan 70GGHFCummins/Onan 75GGHFCummins/Onan 75GGHHCummins/Onan 85GGHGCummins/Onan DFABCummins/Onan DFACCummins/Onan DFBFCummins/Onan DFCB

Related fault codes

Airman fault codesAtlas Copco fault codesCummins/Onan fault codesGenerac fault codesKohler fault codesSDMO fault codes

Common questions

What causes low coolant level?

Common causes, most-reported first: Replenish; Shutdown, Low coolant level, Coolant hoses leaking, Engine block or water pump leaking; Possible Causes: Excessive liner standout. Excessive liner standout differential between cylinders. Low head bolt clamping loads. Out-of-flat/damaged/rough block surface. Out-of-flat/damaged/rough cylinder head surface. Oil or coolant overheating. Cracks/creases in gasket body surfaces. Damage/voids in elastomer beading..