The plugged banjo bolt is to keep vegetable oil from going into the diesel filter. The actual fitting up there looks like this:
=( | | )=

The | | is the bolt and the = are the fuel lines into that round fitting that the banjo bolt slips into. The fuel can flow around the banjo bolt and into the looped return. The plugged banjo bolt just prevents the oil from going into the hole on the banjo bolt, down the hole, and into the diesel filter.

The banjo bolt is not the bleed mechanism by itself. If you want to purge air, you have to loosen the banjo bolt and use the primer pump, then tighten it again.

I hope this makes sense.

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Andrew

1989 Volvo 745- 202K