Why generators show "sharp metallic thud, especially when cold engine first started": 11 documented causes and brand-specific fixes, compiled across 10 manufacturers.
Low oil supply. Oil badly diluted.
3 brands- Cummins/Onan: Add oil to increase the oil supply if it's low. Refill with proper oil if it's badly diluted.; Add oil. Change if necessary. Drain, refill with proper oil.
- Doosan: Add oil. Change oil.
- Onan Electric: Add oil. Change if necessary. Drain. Refill with proper oil.
Low oil supply
3 brands- Cummins/Onan: Add oil; Add oil. Change if necessary.
- Doosan: Add oil
- Ernest: Add oil. Change if necessary. Oil badly diluted, Drain. Refill with proper oil.
Low oil supply, Oil badly diluted.
2 brands- Cummins/Onan: Add oil. Change if necessary. Drain. Refill with proper oil.
- generatorpartspro: Add oil. Change if necessary.
Low oil supply. Add oil. Change if necessary. Oil badly diluted. — Drain. Refill with proper oil.
2 brandsLow oil supply. Add oil. Change if necessary, Oil badly diluted, Drain. Refill with proper oil
2 brands- Garretson: Add oil. Change if necessary, Drain. Refill with proper oil
- NEC: Add oil. Change if necessary, Drain. Refill with proper oil
Low oil supply, Low oil pressure, Oil badly diluted
1 brand- Cummins/Onan: Add oil, Refer to symptom of low pressure for remedies, Change oil
Low oil supply.
1 brand- Cummins/Onan: Add oil.; Change oil.; Add oil.
Low oil supply, Oil badly diluted
1 brand- Cummins/Onan: Add oil, Change oil
Low oil supply; Oil badly diluted
1 brand- generatorpartspro: Add oil; Change oil
Low oil supply. Add oil. Change if necessary. Oil badly diluted. Drain. Refill with proper oil.
1 brand- Cummins/Onan: Add oil to increase low supply. Change oil if necessary and refill with proper type if it's badly diluted.
Low oil supply; Low oil pressure; Oil badly diluted
1 brand- Cummins/Onan: Add oil; Refer to symptom of low oil pressure for remedies; Change oil
Common questions
What causes sharp metallic thud, especially when cold engine first started?
Common causes, most-reported first: Low oil supply. Oil badly diluted.; Low oil supply; Low oil supply, Oil badly diluted.; Low oil supply. Add oil. Change if necessary. Oil badly diluted. — Drain. Refill with proper oil.; Low oil supply. Add oil. Change if necessary, Oil badly diluted, Drain. Refill with proper oil; Low oil supply, Low oil pressure, Oil badly diluted.