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Cummins/Onan GV12-525-1P Engine

The Cummins/Onan GV12-525-1P is a 408 L engine rated at 1800 rpm. It powers generator sets from Cummins/Onan, including the 250 FT. It holds 5.5 L (1.5 gal) of oil and 6 L (1.6 gal) of coolant.

Also known as: Cummins GV12-525-1P

408.0 L
Displacement
1800 rpm
Rated speed
5.5 L
Oil capacity
On this pageSpecsGenerator setsMaintenanceFAQ

Engine specifications

Oil capacity5.5 L
Coolant capacity6.0 L
Displacement408.0 L
Rated speed1800 rpm

Generator sets powered by this engine

1
Cummins/Onan 250 FT

How to read your Cummins/Onan engine serial & model number →

Common problems

6
  • Partial loss of residual in rotor
    Fix: With plant operating, jumper front E2 to heat sink of field rectifier Z until voltage begins to build-up. Then remove.
  • Output voltage slow to build up. Circuit breaker opens in about five seconds.
    Fix: Either field rectifier X or Y shorted. Test rectifiers and replace if defective.
  • No AC power to Magneciter
    Fix: Check AC voltage at E1 - E2 with the plant operating. Voltage should be five percent of the rated voltage. If not, check continuity from E1 -E2 back to generator.
  • Generator will not build voltage.
    Cause: Circuit breaker in 'off' or 'tripped' position.
    Fix: Reset and close breaker
  • Fair of field rectifiers open (either X or Y).
    Fix: Test rectifiers and replace if defective.
  • Both field rectifiers X and Y sorted.
    Fix: Test rectifiers and replace if defective.

Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan GV12-525-1P.

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filterService the crankcase breather air cleaner as outlined in Cummins manual, Section 3.—
Fuel filter—
Oil filter—
CoolantFor units which use either a radiator or heat exchanger (city water cooled), fill the cooling system with clean soft water. Use a good rust and scale inhibitor.—
OilRefer to Section 5 of the Cummins manual.18.0 U.S. gallons—

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Common questions

What is the oil capacity of the Cummins/Onan GV12-525-1P?

The Cummins/Onan GV12-525-1P engine has an oil capacity of 5.5 liters.

What is the displacement of the Cummins/Onan GV12-525-1P?

The Cummins/Onan GV12-525-1P has a displacement of 408.0 liters.

Which generators use the Cummins/Onan GV12-525-1P engine?

The Cummins/Onan GV12-525-1P powers 1 generator set(s), including Cummins/Onan 250 FT.

What is a common problem with the Cummins/Onan GV12-525-1P engine?

A commonly reported issue on generators using the Cummins/Onan GV12-525-1P is: Partial loss of residual in rotor. Fix: With plant operating, jumper front E2 to heat sink of field rectifier Z until voltage begins to build-up. Then remove..