Diesel Fuel in Crankcase

[JS300]

Over the last 100 hrs or so when I check the oil on our dozer I’ve noticed it seems a little over full but nothing alarming so just thought I would watch it. Well today it was obviously over full. I suspect diesel is getting into the crankcase. Oil smells and looks fine. It’s right at the 250 hr mark so I plan on changing it and getting analysis done. This is on a Case 850G w/ 5.9L. Only thing I can figure is fuel pump or injection pump shaft seal. Fuel pump was replaced about 125 hrs ago because old one kept leaking oil at gasket. Am I missing anything? Figure putting the original fuel pump back on will eliminate a bad pump so I will go ahead and do that. I also replaced the injectors 250 hrs ago but engine runs fine so don’t figure it’s injectors.

 

[spark]

could be lift pump diaphragm

 

[JS300]

Only pump I can find is the mechanical fuel pump. I replaced it last year because after a heavy push the engine would sputter a bit when you let off the throttle like it was starving for fuel (easy and cheap fix I thought). The pump I replaced it with always leaked oil at the engine gasket and fuel at the discharge line. I finally replaced it with the current pump which was a Case part instead of aftermarket and now have this problem.

 

[DMiller]

If that is all that is new with no other engine performance issues is time to peel it back off and change the internal seals. Could be something totally unrelated but go there first.

 

[thepumpguysc]

As long as you have 1 on hand & you KNOW its not leaking internally.. change it out..
BUT.. if its NOT the lift pump & you changed your oil already.. that can get fairly expensive..
I wouldn't suspect injectors either IF its running ok & not HEAVY black/white smoking.. [ dumping fuel into a cylinder]
What type of inj. pump is on it?? I can tell you weather or not the front seals are an issue.

 

[JS300]

Here’s a pic pumpguysc. I’m going to change the oil when I get off work in the morning. I’ve got a job to do Monday that should take about 8 hrs. Figure I’ll get that done and see how oil looks.

 

[Coy Lancaster]

Those Bosch pumps are known for front seal leakage after a time. I'm sure that pumpguy will be able to help you out.

 

[JS300]

Dozer has 4,258 hrs on it and pump looks original. Pumpguy helped me out with a leaky throttle shaft seal on this pump already and I have the front seal for it that came with the kit. I hate to change the oil then run it without checking anything but told these folks I would do this job for them. Surely 8-10 hrs won’t leak that much diesel in the sump.

 

[thepumpguysc]

Yea, that's a Bosch VE pump.. KNOWN for the leaking front seal.. & throttle shaft seal, too.
The pump has to be removed to repair.. IF you can find a repair shop close, they can replace the front seal only.. [special tool] relock the timing & back in your hands in less than 1 hr..
Good luck.

 

[JS300]

Thanks for the help. Do I need to take the timing cover off or will the pump slide out gear and all? There is a pump shop about 45 min from me, been needing to take some injectors to them to get tested too

 

[thepumpguysc]

The pump & engine MUST BE TIMED & LOCKED before removal..
The access cover is Unscrewed & the gear has to be POPPED OFF [puller]..
timing is CRITICAL..

 

[JS300]

Changed the oil this morning and it looked and smelled like used oil. It was very high on the dipstick but, judging by how much oil was in the bucket and filter I’m going to guess it was 1-2 quarts over full. I though it would overflow the bucket or be very close. I’m going to watch it until analysis gets back and see what happens.

Thanks pumpguy. I was thinking time and lock pump and figured cover had to come off. I will most likely get dome help or take it somewhere. I would hate to mess it up.

 

[thepumpguysc]

I don't know if you have 1 or not but, an ENGINE TURNING TOOL for a Cummins IS A MUST..
Makes the job 1000 x easier and enjoyable.. Its a knuckle buster otherwise..
Found on ebay for about 30 bucks.. WELL WORTH THE MONEY.. even if doing the job ONCE.
Its a serrated/toothed tool that fits into a hole on the bell housing & turns the flywheel..
WITH THE TOOL, you can time the pump & engine by yourself..
You'll also need a LARGE oil filter wrench or LARGE channel lock pliers to unscrew the access cap, to get to the gear.. ITS TIGHT.

 

[JS300]

Thanks for the advice. I don’t have that tool but looked at one when I ran the valves. Guess I need to get one. I may PM you if I decide to try this alone. It seems fairly straight forward after reading the manual but, I be a nervous sucker till I got it running again.

 

[Coy Lancaster]

There is a round cover on the front of the timing cover, remove it and you'll see a nut that holds the drive gear onto the pump shaft. After you loosen the pump remove the nut, you will need a "T" style puller to use as a pusher to push the shaft out of the gear. Check your local auto parts store some of them have the cummins tools you need and will loan them to you.

 

[JS300]

Thanks. I ordered the barring tool and a puller for the gear. I’m still not sure if it’s the lift pump or the injection pump. Lift pump is new so guess I will go for injection pump first. I figure it’s probably time to get the seal replaced anyway.

 

[thepumpguysc]

I commend you for waiting on the tools.. you'll thank us later..
Once you get the pump off.. you can pressure check the front seal by putting air pressure in the either the OUTLET or the INLET.. just hold your thumb over the other hole & watch the front seal for leakage..
DONT BLAST IT w/ air or you will blow the seal.. about 5psi is enough..

 

[JS300]

I’m just going to take it to the pump shop but thanks for letting me know the seal can be tested. I’ll be sure and tell them to do that. At least I will know if I need to replace the lift pump or not. I’m kinda wondering if the injection pump has been leaking for a good while and the small oil leak on the old lift pump was keeping the oil level right. It was a very small leak from the gasket. I tried to fix it several times with no luck so finally bought the new lift pump.

 

[Coy Lancaster]

A lot of pump shops will want to do a complete rebuild, but if you can get them to just replace the front seal then get them to replace the throttle shaft seal also and calibrate it at the same time.

 

[JS300]

The tools to remove pump came in today. Hopefully I can get the pump off this weekend. I replaced the throttle shaft seal back in the spring, it was leaking pretty bad. The pump shop around here is pretty small and owner operated so I don’t think they will give me a hard time about the seal.