The Fine Art of Bleeding Diesels
A.K.A. How I finally got my diesel
I thought it was simple, loosen the injector nut while cranking, wait for it to squirt, then tighten—not so.
This method did not work, but a subtle variation did work.
First, the problem. Apparently, the issue is that if the nut is loosened too much, the air can be sucked back into the injector by virtue of the fact that a gap can exist between the fuel tubing and the injector due to the nut being too loose.
Tighten the nut enough to preventing air intake—but leave it loose enough that the 2,900 psi will push the fuel past it. But how do I tighten the nut to that magical torque?
1. Loosened the nut ¾ of a turn.
2. Crank the engine until fuel squirts.
3. Continue cranking, and slowly
tighten the nut until snug. I used about 40 seconds to do this.
4. At this point the bleeding is done, and the nut can be torqued to spec.
Why does this work? During this slow tightening, that magical point is reached where there is enough pressure to keep the air out, but allow the fuel to squirt. Since you are slowly tightening the nut over the course of about 40 seconds, it takes five or ten seconds to pass through that magical point, and during that time the bleeding is completed.
This is my own recipe, and I have not seen it anywhere else. Please feel free to comment. I would be interested to see if anyone has had the same experience. Also, has anyone found a similar but better way?
P.S. I should also mention that my diesel
did start spraying fuel from the injector at this point, but would not fire until I pulled the cold weather
start lever (silicone spray and WD40 did not help). I suppose the system needed to get an extra shot of fuel to goose the engine . . . ?