Can you tell me if the IP and injector return lines that meet at the banjo bolt on top of the fuel filter of a 1984 300d mix fuel with the supply side in the filter?

Thanks, Chuck

__________________
1983 300td 240k (down with bad tranny)
1984 300d 222k (daily driver) "Olive"
1997 GMC K2500 105k (sled dog limo)

"The scenery in ANWR is as spectacular as the Grand Canyon and the wildlife is more impressive."

Anyone?

__________________
1983 300td 240k (down with bad tranny)
1984 300d 222k (daily driver) "Olive"
1997 GMC K2500 105k (sled dog limo)

"The scenery in ANWR is as spectacular as the Grand Canyon and the wildlife is more impressive."

ak300dt,

In the top of the fuel filter, under the banjo bolt, there is a small hole to purge any air in the filter, and that is why you don't to have to leave the bolt loose to purge air from the filter. The overflow fuel is not mixed with fuel in the filter because the pressure inside the filter is higher than the pressure in the return fuel lines which have virtually no pressure. So even though the return lines are connected to the filter thru the air purge hole, no fuel will flow into the filter because of the pressure differential and any fuel or air in the return lines flows only back to the fuel tank.

In other words, the banjo bolt is a collection point that allows any air in the filter along with the overflow fuel from the IP and the injectors, to be returned only to the fuel tank.

P E H

Try advanced search, specify diesel discussion forum and keywords: banjo loop

Check the faq over at the SVO forum

Thanks PEH.

I'm installing a two tank wvo system with seperate supply and return lines and filters for diesel and wvo. I want to be sure there is no mixing of veggie with diesel since even a little veggie going to the diesel tank might result in a gelled diesel filter. I'm installing two 3 port valves to allow a few minute diesel purge of the IP and injectors that flushes back to the wvo tank.

With the filter side of the assembly under pressure and the return side not under pressure, I would assume the bleed hole always leaks some fuel into the return lines. That would be an avenue for wvo to make it into the diesel circuit. Make sense?

I was hoping to plumb the return fuel line from downstream of the banjo bolt to the 3 port valve, but it seems like I'll have to connect the IP and injector return together, run them through the valve then back to either the banjo bolt or to the wvo return side depending on whether the valve is energised or not.

Thanks for the advice! Chuck

__________________
1983 300td 240k (down with bad tranny)
1984 300d 222k (daily driver) "Olive"
1997 GMC K2500 105k (sled dog limo)

"The scenery in ANWR is as spectacular as the Grand Canyon and the wildlife is more impressive."

ak300dt,

Yesit makes sense that some fuel is always going thru the bleed hole and back to the tank and that is what actually happens.

But I don't believe a small amount of WVO getting into the Diesel fuel will hurt anything. Any gelling in the fuel filter will melt when the underhood temperature exceeds 50*F and pass thru into the IP and engine and be burned.

P E H