955H Fuel Return Line:

[garythomak]

Hi all,
I have a 955H, S/N 60A10479. I recently replaced the engine and can't seem to remember where the fuel return line connects. It is possible it was never connected, after starting it up I happened to notice a small amount of fuel leaking and determined from the service manual that it was the return line. With the price of fuel, can’t afford to waste a drop now!
I thought usually these went back to the tank on a separate line but according to the book, it doesn't. It did not have a priming pump on it in the beginning and Cat told me to attach that to the line coming from the tank. I think I changed the fitting to do that but can't remember. Would this work, attach the return to the line coming into the pump from the tank?
Thanks,
Gary
garymisc@wildblue.net

[Old Magnet]

I don't believe there is a fuel return line. Just the supply line coming from the tank. If you have a priming pump there is a tee fitting just before the transfer pump to supply the hand pump.
There are two open drip indicator lines.
One is the vent line for the fuel filter housing and the other is the drain for the cavity between the seals of the fuel transfer pump. That may be the source of drip on your unit.

[garythomak]

Thanks, I found the vent line and it seems ok,the one that is leaking is at the bottom of the fuel filter housing. The line from the tank goes into a fitting just in front of it.
Is the vent line (it has a shutoff) for manual use? When I primed the fuel filter I opened the shutoff until I started getting fuel then closed it off and continued to pump it until I had some pressure showing on the guage. It started right up so am assuming this is the purpose of the shutoff.
Gary

[Old Magnet]

Yes, the manual valve is for venting air/fuel from the filter housing. Open until you get a bubble free stream of fuel in combination with pumping. These valves are usually pretty reliable until somebody over tightens and buggers up the needle stem.

[bob]

OM, older cat machines that had the fuel tank high enough that the fuel level did't get below the pump didn't have a fuel return line. Dozers and loaders.
Wheel loaders, scrapers and excavators that had lower tanks did. It was for constantly bleeding any air picked up by the pump back to the tank. All of the machines with the New Scroll fuel system have return lines.
Later Bob

[Old Magnet]

Thanks Bob,
I kind of thought that was the way the fuel system was routed on the 955H but my 60A8413-13741 Parts Book does not show any detail on the fuel tank or tank plumbing so I didn't want to make a definite statement.