I attached a picture (Disregard the name tag on the pic; it's not the heating element!) of a covered port on the rearward side of the fuel filter housing on D2 5U engine. It's the one covered by a two-bolt plate near the top of the main casting. Question anybody: Is this the port they used when a return line to the fuel tank was used, when this engine was used as a D311 stationary power plant? It looks like it would work; it opens from the top of the lower filter chamber.

Some of you have been around this BB long enough to recall that I'm building a waste vegetable oil fueled generator plant. Circulation back to the tank would help a lot to keep the oil hot. By the way, the plant is nearly complete and should be running within the next month, thanks to a lot of help and advice from this BB.

So, how about a little more advice? Thanks,

Jack

Hi Jack,
Was wondering when you'd get back to that project....seems you are making good progress.

Yes on tapping that port for return.
Industrial and gen set engines have the fuel pressure relief valve mounted at that location with return to the tank. The transfer pump just has a direct feed (no relief valve housing) like the tractors.

By golly, that was fast! Thanks, OM.

I think I can make a fuel line adaptor without the pressure relief and a return line fitting with the relief from the D2 pump fitting faster than I can run down real D311 parts. I just didn't want to do either until I was sure it would work. Everything else on the front of that engine is modified. Why quit there?

No reason why not.....and probably just as well that you make your own as it's none to clear in the parts book for the either the D311 or D315 but clearly shown in the operators manual.

Jack, modern Cat engines have fuel return lines but the older machines didn't have them unless the fuel tank was mounted where the fuel level could get below the fuel pump. Industrial engines could have the tank mounted anywhere so they all had a return line. The return line will return any air picked up by the suction line to the tank and provide Constant Bleeding.
Later Bob

Bob, I never thought of that remote tank issue, had just figured on placing the tank on legs high enough to feed like on a tractor. Makes sense.