Engine/Transmission (1994 - 1998) lift pump

[nfox]

is there anything to watch out for when changing out the lift pump? Mine is just started to seep. Where is the best place to pick one up, and what do they cost$

 

[JGK]

nfox,



I believe they are around $165 from Cummins, but I saved a little by buying mine from the Kenworth dealer (Cummins gives a break to their main customers).



There is a plunger that works off the cam to actuate the pump. Be real careful when pulling the pump away from the block after the bolts are removed that you don't lose the plunger inside and down into the pan. There is some friction that holds it in the pump, but not a lot. Just be careful.



I was told to use the original plunger since it has properly worn in with the cam lobe. Put a dab of grease on the end when reassembling.



The manual told me to bar the engine over to a particular point get the cam at the lowest point. After fighting with trying to get the 2 screws started that hold the pump on for nearly an hour in a very awkward position, I pulled it out, put my finger in on the cam, and had my wife bar the engine over. Sure enough, the manual had it just 180* off. The cam was at the high point. Once that was corrected, it took me about 5 minutes to get the bolts started.



Check this link link for a good write-up on it by CJ Johansson.



-Jay

 

[nfox]

Thanks for the information JGK Oo. Oo.

 

[Dieselnerd]

12 Valve Lift Pump, latest style, Cummins P/N 3936316



I paid $160. 45 including tax at Cummins. This P/N is about the third revision according to the parts guy. It's a different manufacturer and larger than my original. I did not use the old push rod, I used the new one that came with the pump. I figure if you were supposed to use the old, they wouldn't provide a new one.

 

[Joe G.]

nfox,



Before buying a new lift pump check to make sure where it's leaking. It may just be the manual push button. If that is the problem the O ring to fix it only costs about 50 cents. The stock O ring is kind oval in cross section, but a round one works fine.