(7)Needle valve and needle valve hole guide surface abrasion

The needle valve moved in the needle valve hole frequently and reciprocately, in addition the diesel  impurities and dirt will make the needle valve hole guide surface abradant, so that the inside gap increases or scratch the needle valve, caused the injector leakage increased, pressure reduction, fuel injection volume reduction, fuel injection time lag, resulting in diesel engine start-up difficulties.
Solution: When the fuel injection time delay too much, the vehicles can not even run, at this time should replace the needle valve.

(8)oil droping of the injector

When the injector is working, thesealing cone of needle valve body will be subjected frequently strong impact by needle valve, And high-pressure oil spray from the cone constantly, it will gradually appear scratch or spots, resulting in loss of seal, cause the fuel injector drip oil.
When the diesel engine temperature is low, the exhaust pipe appears white smoke, when the machine temperature rises then becomes the black smoke, the exhaust tube will emit the irregular blasting sound. If the cylinder is stopped to provide oil, smoke and noise will disappear.
Solution:  Disassemble the injector, dip a little chromic oxide fine  grinding paste in the needle valve heade (note the paste can not touch in the needle valve hole)  grinding on the cone, and then wash into diesel, then install in the injector to test. If still not qualified, you need to replace the needle valve.
Please check other article related 8 Common faults of diesel injector: