What causes oil leakage from the installed fuel injector?
2 Answers
The reasons for oil leakage from the fuel injector may include dirty engine oil, excessive engine temperature, damaged gasket, low injection pressure, etc. Dirty engine oil: Unclean engine oil with impurities in the high-pressure oil pipe can cause the needle valve assembly to fail to close tightly, allowing high-pressure combustion gas to backflow and damage the needle valve assembly. Additionally, contaminants on components such as the injector pressure regulating spring and tappet can contribute to this issue. Excessive engine temperature: Poor cooling of the injector due to high engine temperature can lead to seizure of the fuel outlet valve assembly. Other contributing factors include delayed fuel supply timing, excessive scaling or blockage in the cooling water passages, wear on the water pump impeller end face, or prolonged engine overload. Damaged gasket: During fuel injector installation, missing or damaged gaskets can cause air leakage, resulting in localized overheating of the injector and subsequent seizure. Low injection pressure: Insufficient injection pressure can cause high-pressure combustion gas in the combustion chamber to backflow.
I've worked on many cars and have often encountered oil leakage after installing fuel injectors, usually because the injector seals have aged or were installed incorrectly, allowing oil to seep through gaps. The fuel injector area is supposed to be well-sealed, but over time, the rubber seals can crack. If you rush during installation and don’t align them properly, oil will leak. It’s also important to check the oil pressure—if the pump pressure is too high, oil can be forced into places it shouldn’t be. I recommend removing the fuel injectors, replacing the seals with new ones, and tightening them with a torque wrench according to the manual specifications. Don’t delay too long—if the leak worsens, oil dripping onto the exhaust pipe could cause a fire, leading to serious trouble. It’s best to wipe away any oil residue with a clean cloth and check for scratches or debris blocking the surrounding area.
