Fuel in oil 8.3 common rail in 2588

[dale560]

A buddy of mine bought a 2588 combine a couple years ago. He hasn’t really used it much because a fault code would derate it when cold. This combine was always a local machine and he bought it really cheap at a consignment sale. Combine is actually really pretty nice shape. It had issues with the previous owner who was second owner. The local caseih dealer had changed injectors in it in 2017 apparently. He asked me a few times about his issues and I looked symptoms up online and found a Cummins service pamphlet actually. He had the actual Cummins dealer come out with insite program and they changed 4 of the injector pass through tubes last week. They noticed rail pressure between two sensors was not quit right. The 4 tubes they changed helped it a lot. The other two he didn’t have manifold gaskets so left them. It cured the check engine light but now after running combine it is filling crankcase over full.  The only place they can leak fuel is through the injectors isn’t it. The pass through tubes only leak into return system if I understand right. Do any of you know common places for fuel leaks. The local caseIH dealer won’t work on it they spent a bunch of time over the years trying to fix their mistake apparently. So just wondering if fuel going out pump drive shaft or up through injectors. I haven’t touched machine but he is very good friend and just want to help him out. Years ago I fixed a n14 for him that I had to run dye in fuel. He bought a nice semi cheap knowing it was leaking. The previous owner had injectors and pump changed it kept leaking. After running dye two rebuilt injectors were pushing fuel up out into valve train. 
 

it would use injector and transfer tube like these. I guess I am asking the only way fuel could leak into crankcase is through injector top or high pressure pump shaft right? Or is return pressure enough to force it by oring on injector?

[bwop2017]

Its possible that the injector "quill/feed" tubes are loose and not sealing, and dumping pressurized fuel past the injector o-ring which seals the return fuel from the rocker area. I've noticed that over time the quills can loosen up from heat cycles and vibration. Over-torque them. I usually go 2-3 ft. lbs. over spec. I think spec is 35. I modified a line socket so I can do them without having to take anything apart.

[HydroTek]

When that happens , there is too much fuel return in the line at the rear of the head

also you can feel the heat in the return 

Return can push past the oring if it is excessive -- or the ring is old/hard
remove the line at the rear of the head and run the engine -- should be just a dribble 

Also can run the engine without the valve cover and see if fuel is pushing up past the injector oring 

only ever had a couple of those pumps leak 
but these are getting old now
so shaft seal could be the problem

This engine have the electric lift pump ?
or the mechanical ?

[SDman]

[dale560]

13 minutes ago, SDman said:

Thanks Jim. That is the info I can tell him. My buddy has other combines he likes to buy 1680s and 88s at sales. He bought this 2588 at a local consignment sale. Our neighbor owned it for a couple years brand new. He and his dad had matching combines they customed combined with.  Both got traded at local dealer and this one stayed local the other one went about 50 miles away. My buddy bought it three years ago. Didn’t use it except his son ran it a bit and last year the same thing. They noticed the check engine light would come on and derate at times. I told him it probably needed injectors at its age. His son is buddies with service guy at local dealer. They gave up on trying to fix this combine and won’t look at it anymore. They don’t want it in shop and won’t come out with computer to look at it. I told buddy if needed I could get computer with insite from my truck buddy and even have his shop guy come along to hook it up. He had two or three truck and tractor repair guys try and hook up to it with generic tools none of them would read anything. He finally got frustrated and got the Cummins dealer to come out. They got it fixed with the fuel crossover tubes to keep check engine light off. But after running it a couple days it’s making oil.  now I can tell him where to look and if he can wait a bit I will run some dye in and check out the injectors.

[dale560]

Just to be clear. They didn’t pull the valve cover and mess with the injectors this time. The Cummins guy who was really good he was a JD mechanic originally hooked up inside checked the codes and parameters then replaced 4 of the transfer tubes. He said they were abnormally rusty on the retaining nut and tube area.