John Deere — Test Fuel Injection Nozzles

Testing & diagnosis

From a John Deere service manual covering: 4045, 4045TF120, 6068, 6068TF120, 6068TF250, T06068TF220, T06068TF250, T06068TFM50. Check it applies to your exact model before use.

Applies to: John Deere 4045, John Deere 4045TF120, John Deere 6068, John Deere 6068TF120, John Deere 6068TF250, John Deere POWERTECH 4.5 L & 6.8 L Diesel Engines (4045 / 6068) engine

Procedure

1. Connect injection nozzle to nozzle tester.
2. Position tip of nozzle below top of beaker and back out 30 degrees from vertical.
3. Pump handle several strokes to flush air and determine pumping rate required for atomization.
4. Opening pressure test: actuate tester rapidly several times to seat valve.
5. Raise pressure until gauge needle falls rapidly; record nozzle opening pressure.
6. Compare readings to nozzle opening pressure specifications for new or used nozzle.
7. Chatter test: close gauge shut-off valve and operate tester at a rate that causes nozzle to chatter.
8. Operate tester for ten strokes; nozzle must atomize on at least eight strokes without consecutive misses.
9. Spray pattern test: observe pattern and check for plugged, chipped, or eroded orifices.
10. Leakage test: position nozzle tip down, seat valve rapidly, wipe tip dry, raise pressure below opening pressure and hold.
11. If fuel drips from nozzle within 5 seconds, nozzle must be lapped.

Full service-parts list: John Deere 4045 →, John Deere 6068 →, John Deere 6068TF250 →

Source: John Deere service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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