by Turbo67 » Thu Aug 13, 2015 9:00 pm
Worked on the leak again this evening.
Removed the injector and examined the sealing surface where the return goes and the corresponding surfaces of the horseshoe washer. The washer did not seem to have a consistent crushed surface all around it. The injector sealing surface had some un-even spots and needed stoning and in a couple of minutes and it was flat again. Use a machinist's fine flat stone. Did the same to the return line banjo fitting for this cylinder. That was a little more difficult as it was still attached to the other 5 injectors. So I just carefully took a few passed on it till it was lightly cleaned up.
I then examined the banjo bolt and screwed it into the injector on the bench. Bolt started, but then got tight after about 2-1/2 turns. Broke out the dial caliper and measured the distance between the sealing face of the bolt and the injector body. Then compared that number to the combined thickness of the return line fitting and horseshoe copper washer. Turns out the bolt was becoming tight before adequate crush was being achieved on the washer. I had been reluctant to just keep tightening the bolt as it felt plenty tight. It is only about an 8mm or so diameter and I did not want to break it off in the injector. I worked the bolt in and out of the injector deeper and deeper each time to learn just how many turns I could go before it actually bottomed out. I counted the turns to achieve a little less space between the face and the injector body as compared to the overall thickness of the banjo fitting and washer. Then re-assembled everything, taking careful note of how many turns I applied to the banjo bolt. Snugged it all up and all is now dry!
I guess I could have just tightened till the leak stopped, but at the time I did not know what was wrong.
Through this experience I became familiar with the internals of the injector, so if I ever decide to replace the nozzles or set the pop off pressure, I know how it all goes together.
I also learned that old injectors that have been in place for a long time, need liberal soaking in a suitable solvent to loosen the rust. My hold down nut was locked to the injector body. I was not aware that these injectors have a ball bearing that aligns them with a slot in the head. I thought the nut was welded / machined into the injector body, not so! Learn from my mistake, soak things good, maybe apply propane torch heat, soak more. I nearly damaged my cylinder head and did damage the ball bearing in the injector body removing the nut as the injector "screwed out" with the nut. Not a good thing to have happen.
Turbo67
93 Cummins 5.9L, VE Pump, 300,000 miles
4200 RPM Spring, indexed stock fuel pin, Fuel Screw maxed, then replaced with longer "Hot Screw", aneroid screw tweaked