John deere 1520 fuel in oil

John deere 1520 fuel in oil

Likely Cause: Worn or Failing Injection Pump Seal

The umbrella seal in the injection pump prevents fuel from leaking into the crankcase. If this seal is damaged or worn, especially after prolonged exposure to thin oil, diesel can seep into the crankcase and contaminate the engine oil.

John Deere 1020 1520 1530 2020 Tractor Service Manual

How to Inspect and Address This Issue:

1. Confirm the Source of the Leak:
   • Check for signs of fuel dripping from the injection pump or around its mounting point.
   • Remove the injection pump and inspect the driveshaft area for excessive wear or a damaged seal.
2. Replace the Umbrella Seal:
   • Disassemble the injection pump (or have a professional service it if you’re not experienced).
   • Replace the damaged seal with a new one. Ensure all seals are installed correctly.
3. Inspect the Pump Driveshaft:
   • Check for grooves or wear on the driveshaft where the seal makes contact. If it’s worn, replacing or resurfacing the driveshaft may be necessary.

Other Possible Causes to Consider

1. Faulty Lift Pump (Again)

Even though you replaced the lift pump, it’s worth confirming the new one isn’t defective or improperly installed. A damaged diaphragm in the lift pump can allow fuel to bypass into the crankcase.

• Solution: Test the lift pump for proper operation and replace it if faulty.

2. Injector Issues

Leaking injectors can cause fuel to mix with oil indirectly, especially if they over-fuel the engine and wash down the cylinder walls.

• Solution: Remove and test the injectors for proper spray patterns and pressure. Replace any faulty injectors.

Next Steps After Repairs

1. Drain and Replace Oil Again:
   • Thoroughly clean out the crankcase by draining all contaminated oil. Replace with fresh oil and a new filter.
2. Monitor Oil Level Closely:
   • After completing the repairs, monitor the oil level during operation to ensure the issue is resolved.
3. Consider Professional Help:
   • If you’re unsure about repairing the injection pump or diagnosing the problem, a certified John Deere technician can perform a detailed inspection and rebuild the pump if needed.

Preventive Maintenance Tips

• Always ensure seals and gaskets are in good condition during routine servicing.
• Check the fuel system regularly for leaks or signs of wear, particularly around the injection pump and lift pump.
• Avoid running the engine with low oil levels or excessively thin oil for extended periods.

By addressing the injection pump seal and ensuring the lift pump and injectors are functioning properly, you should be able to resolve the fuel contamination issue and keep your John Deere 1520 running smoothly.

John Deere 1020 1520 1530 2020 Tractor Service Manual