3116/26 leaking fuel primer pumps

[The Bill Collector]

I have 3126's Cat's and I know there are lots of other CAT owners out there too.... My starboard engine drips a little, but the port engine has a bit more then I like to see...

It looks like it is coming up the piston of the little hand primer pump located by the on engine fuel filter...

Has anyone else dealt with this drip and what is the fix ??

Thank you in advance, Mark

 

[fwebster]

Yep............

The problem most likely isn't the priming pump, but the little knurled valve on it that open the flow to the pump. Those pumps are not fuel tight and will always leak a little when they et a few years on them. The knurled knob is on the stem of a ball valve that completely shuts off the pump. Sometimes the knob slips on its shaft and you cannot tell if its open or closed. If you turn the valve a little it, will stop the leak, provided you guessed the correct way. If you didn't, its going to be a trial and error thing.

This is yet another reason I don't prime my engines with the pump....I'm tired of fooling with them. And, yes I've read the manual and know what Caterpillar says.

 

[The Bill Collector]

Thanks Frank, I kinda figured I wasn't in virgin territory here.... I was considering pulling them off... My thought was there is an O-ring in there to be replaced ? I haven't seen Cat's schematic yet.....

And yes, the little on/off knob located by the pump... If it is a ball valve, then what would be the fix for it ? (total replacement ?)

 

[fwebster]

Re-read my post. Nothing is wrong and nothing is leaking other then the ball valve is open (most likely partially open) which allows fuel to enter the priming pump and the priming pump has no seals on the shaft, so its gonna leak until you close the ball valve.

The fix would be to insure the ball valve is closed and the passage in the ball is 90 degrees to the passage in the body. You can remove it so you can see it, then mark both the knurled knob and the shaft it is pressed onto so you know the position of the ball in the passage if you want to continue to use it. Or, you can get it closed and the leak stopped then not mess with it again and prime your secondary filters manually in the future.

I went thru this 5 years ago on my boat. Once I got the ball positioned right, mine don't leak and haven't since 2003. I prime my filters by hand.......which BTW is much quicker and easier plus its easier on the starter since I never found priming with the pump to be all that satisfactory in the first place.

 

[The Bill Collector]

Frank, I will re-visit the on/off knob. I was sure it was in the off and fully closed position. (When closed the pump compresses air and then when released just pops back up.... When it is open and you pump it you are pushing fuel thru it and I thought I knew the difference.) I will try again and hope for the best (your result).

Thanks again, Mark

 

[Warren]

If you have turned the little stopcock (knurled valve) 1/4 turn the fuel should be shut off. I replaced one pump as it was not working properly - pump, pump, pump and no suction - an inexpensive job (well under $100 to my recollection). But if that stopcock is off - you can fully remove the pump, with no dripping.

Whoops, didn't read on - expert advice give here before my post..
Good luck,
Warren