Why generators show "high oil pressure": 25 documented causes and brand-specific fixes, compiled across 14 manufacturers.
Oil too heavy
8 brands- Continental: Drain, refill with proper oil.
- Cummins/Onan: Drain, fill with proper oil; Drain, refill with proper oil
- Doosan: Drain, refill with proper oil
- Ernest: Drain, refill with proper oil
- Garretson: Drain, refill with proper oil.
- Guan: Drain, refill with proper oil
- NEC: Drain, refill with proper oil.
- generatorpartspro: Drain, refill with proper oil
Oil relief valve stuck
8 brands- Continental: Remove and clean.
- Cummins/Onan: Clean by-pass. Replace if needed; Clean by-pass. Replace if needed.
- Doosan: Remove and clean
- Ernest: Remove and clean
- Garretson: Remove and clean.
- Guan: Remove and clean
- NEC: Remove and clean.
- generatorpartspro: Remove and clean
Defective oil pressure gauge
8 brands- Continental: Replace.
- Cummins/Onan: If not zero when unit not operating, install new oil pressure gauge; Replace
- Doosan: Replace
- Ernest: Replace
- Garretson: Replace.
- Guan: Replace
- NEC: Replace.
- generatorpartspro: If gauge does not read zero when unit not operating, install new oil pressure gauge
Clogged oil passage
8 brands- Continental: Clean all lines and passages.
- Cummins/Onan: Clean all lines & passages.; Clean all lines and passages
- Doosan: Clean all lines and passages
- Ernest: Clean all lines and passages
- Garretson: Clean all lines and passages.
- Guan: Clean all lines and passages
- NEC: Clean all lines and passages.
- generatorpartspro: Repair
Improper oil classification
4 brands- Doosan: Drain crankcase and refill with correct oil.
- Ingersoll Rand: Drain crankcase and refill with correct oil.
- John Deere: Drain crankcase and refill with correct oil.
- Katolight: Drain crankcase and refill with correct oil.
Stuck or damaged filter bypass valve
4 brands- Doosan: Remove and inspect filter bypass valve. See your John Deere engine distributor or servicing dealer.
- Ingersoll Rand: Remove and inspect filter bypass valve. See your John Deere engine distributor or servicing dealer.
- John Deere: Remove and inspect filter bypass valve. See your John Deere engine distributor or servicing dealer.
- Katolight: Remove and inspect filter bypass valve. See your John Deere engine distributor or servicing dealer.
Stuck or damaged oil cooler bypass valve
4 brands- Doosan: Remove and inspect oil cooler bypass valve. See your John Deere engine distributor or servicing dealer.
- Ingersoll Rand: Remove and inspect oil cooler bypass valve. See your John Deere engine distributor or servicing dealer.
- John Deere: Remove and inspect oil cooler bypass valve. See your John Deere engine distributor or servicing dealer.
- Katolight: Remove and inspect oil cooler bypass valve. See your John Deere engine distributor or servicing dealer.
Oil pressure regulating valve failure
3 brands- Doosan: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
- Ingersoll Rand: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
- John Deere: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
Oil pressure regulating valve bushing loose (wanders)
2 brands- John Deere: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
- Katolight: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
Improperly operating regulating valve
2 brands- John Deere: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
- Katolight: Remove and inspect oil pressure regulating valve. See your John Deere engine distributor or servicing dealer.
Plugged piston spray jet
2 brands- John Deere: Replace piston spray jet. See your John Deere engine distributor or servicing dealer.
- Katolight: Replace piston spray jet. See your John Deere engine distributor or servicing dealer.
Incorrect grade of lubricating oil; Inaccurate gauge; Pressure relief valve sticking closed
2 brandsDefective gage
1 brand- Cummins/Onan: Replace; Replace.
Oil too heavy grade
1 brand- Cummins/Onan: Drain. Refill; Drain. Refill.
Clogged oil passages
1 brand- Cummins/Onan: Clean all lines & passages; Clean all lines & passages.