The banjo bolt is the air bleed mechanism? - PeachParts Mercedes-Benz Forum

ChefHugh3 · #1 03-23-2007, 05:32 PM

Hey Pizza Chef. I've been running WVO for almost two years. Never had that banjo bolt plugged. I believe the pre filters get rid of the big stuff. Have loosened the bolt to bleed the fuel pump system. Crack it open and pump on the primer until no more air appears, for me it's about 25-30 pumps on the primer. I flush the pre filters about every two weeks with RUG after I had a charcoal filter fail in my WVO filtering setup. Every change has less material. Hopes this helps. Good luck on the wiring/fuses.

Quote:

Originally Posted by pizzachef

I'm trying to figure out something that I read on here some time ago. That is the banjo bolt on top the fuel filter is how air gets bled from the fuel system. If this bolt is plugged (for WVO use) how does this eliminate the air bleed mechanism? Doesn't the air in the system just go around the bolt and right to the tank with the fuel?

All I can figure is the fuel would normally drop into the filter and get looped back into the IP. This would lessen the amount of fuel that needs to be drawn from the tank. (I guess the air goes back to the tank or builds up in the top of the filter...I haven't gotten that far.) But it looks like the load on the IP is decreased with an active banjo bolt.

With a blocked banjo bolt, all of the diesel is returned to the tank, none drops into the filter, and carries the air with it. But a lot more fuel is pumped. Is this bad? If you run primarily on WVO that is looped, the load on the IP should be the same as it was originally with an unblocked banjo bolt.

Am I missing something?

cavaliers16 · #2 03-23-2007, 05:53 PM

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.

ChefHugh3 · #3 03-23-2007, 06:52 PM

The banjo bolt your are asking about is the one on top? This is the one I use to bleed the fuel pump/primer system (sorry if the word description is incorrect)

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pizzachef · #4 03-23-2007, 07:13 PM

Quote:

Originally Posted by ChefHugh3

Hey Pizza Chef. I've been running WVO for almost two years. Never had that banjo bolt plugged.

I guess you're running a single tank system then? There'd be no reason to plug the bolt if so.

But for a two-tank system, you have to plug the bolt to avoid cross-contamination.

Quote:

Originally Posted by ChefHugh3

The banjo bolt your are asking about is the one on top?

Yes, that's the one I'm talking about.
So you loosen that bolt and pump the primer to bleed? Wouldn't that still work with the bolt plugged? The fuel would still have a way to escape out the top. But maybe the vegoil would sneak down past the loosened threads into the filter...hmm..more things to consider...