- Leaking seals on the body or the sleeve of the unit injector
- Excessive leakage from the unit injector tip or a broken unit injector tip
- Cracked cylinder head or leaking cylinder head gasket
- Leakage of the drive shaft seal on the fuel transfer pump
Leaking Seals on the Body or the Sleeve of the Unit Injector
Check the torque for the unit injector clamp retaining bolts. Ensure that the unit injectors are properly installed into the cylinder head.
If damage to the unit injector sleeves or to the O-ring seals is suspected, remove the unit injectors and/or the unit injector sleeves. Inspect the O-ring seals and the unit injector sleeves for damage. Replace any seals or sleeves that show evidence of leakage.
Excessive Leakage from the Unit Injector Tip or a Broken Unit Injector Tip
Look for signs of damage to the unit injectors. If necessary, replace the unit injectors that have damaged tips.
Cracked Cylinder Head or Leaking Cylinder Head Gasket
Check for symptoms of a damaged cylinder head or cylinder head gasket.
Inspect the cooling system for contamination of fuel. Inspect the crankcase for dilution of the engine oil. This may be a sign of a cracked cylinder head or of a leaking cylinder head gasket.
Leakage of the Drive Shaft Seal on the Fuel Transfer Pump
Ensure that the weep hole for the fuel transfer pump is not plugged. Inspect the front of the pump for signs of leakage. If necessary, repair the fuel transfer pump or replace the fuel transfer pump.