John Deere – 1023E, 1025R and 1026R – Cylinder Compression Test – 3TNV76 and 3TNV80

To determine the condition of the pistons, rings, cylinder walls and valves.

JT01682 Compression Gauge Assembly
JDG472 Adapter

[1] – Run engine for 5 minutes to bring to operating temperature. Shut off engine.

[2] – Remove injection nozzles.

[3] –

[4] – Install JT01682 Compression Gauge Assembly and JDG472 Adapter in injection port.

[5] – Disconnect fuel shutoff solenoid electrical connector on rear of governor.

[6] –
Avoid Damage! DO NOT overheat starting motor during test.

Crank engine for three seconds with starting motor.

[7] – Record pressure reading for each cylinder. Compare readings to specifications.

Pressure listed is for 300 meters (1000 ft) above sea level. Reduce specification an additional 4% for each 300 meters (1000 ft) of altitude above this level.

– If pressure reading is below specification, squirt clean engine oil into cylinders through injector ports and repeat test.
– If pressure increases significantly, check piston, rings, and cylinder walls for wear or damage.
– If pressure does not increase significantly after retest, check for leaking valves, valve seats or cylinder head gasket.