Cummings 100 KW Generator

Kohler Gen Set w/Cummings Engine Engine build date 7-25-87 M/N 4B 3.9 S/N 44212215 1200 Hrs Fuel is mixing with oil. replaced lift pump. Checked the IP with lower cover of under pump Can't see it leaking Oil will gain bout 1/4" hr. Rather than guessing, thought I would throw it out to the guros that have helped me before with other issues. The engine starts with 1 turn. No smoke

Have you checked for a bad injector

Cummins. Off the top of my head, I can't think of any way fuel can get to the oil aside from the lift or injection pump. Or a massive injector issue, but that would be very apparent when running. It's been 2 or 3 years since Iast had an old 4BT apart though. (Older Trackless MTs use them)

IceHole said: Or a massive injector issue, but that would be very apparent when running. Click to expand... Might not be ..but i have seen it on a yanmar genset

bobatack said: Might not be ..but i have seen it on a yanmar genset Click to expand... To put a couple quarts of fuel in the oil per hour though?

Yes The engine would shut down for low oil pressure in 1/2 to 1 hour (being diluted with fuel) First was change the fuel lift pump ... no change 2nd was new injection pump ... no change I was send to jobsite and noticed as I walked into the generator room that it is certainly miss firing

With fresh oil. Pressure 70-75 Then it’s starts to dilute and slowly drops. Took another look at the IP with cover off under pump. Seems to be a lot of splatter around the area. Did the paper spot test. Couldn’t really tell with fresh oil. With 1200 hours, hard to believe the seal is bad. Original fuel pump. No IP housing over pressure from wrong pump pressure. Anyway to actually test before removal. Mirror no help

bobatack said: Have you checked for a bad injector Click to expand... No Could not see how injector could dump that much fuel in oil with belching smoke. Thing runs like a top.

Unless you’re going to attempt the inj pump oil seal replacement yourself, be sure to set and lock the timing using the timing pin under the pump.. because if u end up getting a new/reman pump or take it to a shop.. it’ll come back with the drive shaft locked to #1 compression stroke.. (Timing set and locked) If ur going to attempt the repair yourself, u can lock the pump anywhere you like.. Replace the seal and put it back on in the same spot.. Good luck

Pulled the pump. Did all the pre pull. Locking the gear. Locking the pump. Pushed the plastic pin back out. There are 2 seals in the pump. Lot of crap between the 2. Looks like it was leaking. Ordered new seals from McMaster Fingers crossed. Cummings has good info on that subject. Lot of different torque values on the shaft nut. Plus there are 4 different seals for that pump. No dimensions listed either. I figured it out with the mikes.

5393-252R..(2) correct seal #. PAY ATTENTION to which way they go.. there’s A FEW different ways they’ll go.!!

thepumpguysc said: 5393-252R..(2) correct seal #. PAY ATTENTION to which way they go.. there’s A FEW different ways they’ll go.!! Click to expand... Yep. All taken care of. You did the pump for my Yanmar. I have a CaT 306 That leaks oil round the throttle stem. Nipentedo pump. That an easy fix. Leaks a little oil on starter

** Update. Re placed the 2 drive seals in the IP. Started right up after bleeding. Ran for 3 hours @1800 rpm. NO diesel fuel in the oil