07 int cummins isx

90% bad injector o-ring, 10 % cracked head. usually people change all O-rings on injectors. if bubbles are seen again then the head must be taken off for testing. this is common issue with O-rings if engine works in hot states and hauls heavy loads. Cummins has service letter about this issue related to injector O-rings.

 

Does the ISX engine inject oil into the fuel system ?

Submitted: 5 years ago.
JCTECH, Diesel Mechanic
Satisfied Customers: 387
Experience: 31 years experience as a Diesel Mechanic, 14 years at Cummins, good with electronic control systems
HiCustomer
If your engine is fitted with Centinel, the answer is yes the engine does send oil to the fuel system.
The Centinel system act as a type of self changing oil system, extending (not eliminating) oil drain intervals. It sends 17cc of used oil to the fuel tank for burning per stroke of the Centinel plunger and refills 17cc of clean oil from a make up tank into the oil pan.
the number of strokes per hour/mile depend on engine operating conditions.

If your engine does not have Centinel fitted, the answer is no, and I would ask why you suspect you have oil in the fuel system, is it black? if so have you checked for diesel bug?
If you have checked for diesel bug, is there soot in the fuel?
How often do you change your engine oil?
Do you sample your engine oil, if so how much soot in the engine oil?
I have seen black fuel on a different engine range

The fuel pump has a double seal system with a weep hole between the seals, so very unlikely oil is entering the fuel pump.
A leaking injector seal could cause soot to enter the fuel via the return gallery, however the gas would have to travel through both the metering and timing passages which would give very noticeable performance issues, low power and white smoke.

There are dye additive testers to check for combustion gas in fuel/oil/coolant

Hope this helps
John

Customer reply


Not sure if it has the Centinal system. This is the only ISX in our fleet and we haven't had it that long. I don't think it has a diesel bug because although it does have a slight miss at start up, it goes away once the engine is warm. But we'll check

We do sample our oil and there was no soot. we do the oil change at 15,000 miles or at least we schedule it at 15,000 miles, getting it in here on time is another problem. Thanks for the help



JCTECH, Diesel Mechanic
HiCustomer
The reason I asked about oil drain and soot, is because high soot levels in the oil shows up as discoloration the fuel, if there is a lot of oil migration down the injector plunger. This migration is normal and is required to lubricate the injector, and if the oil drain interval is maintained, soot is low and no fuel discoloration is observed.

Regards
John


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Hey Pete read that. My engine guy suggested putting engine oil dye in to the oil and running the engine to let the oil flow. Then check the fuel with a black light to see if dye is in the fuel.

 

What I have been told and have been reading is that if it is engine oil in fuel then
1. Bad injector -you did cut out test already.
2. Failed injector o rings.
3. Failed injector seals.
4. Cracked head.
They would know right away if you had the centinel system.

 

when last time you checked oil level? was it low ? what was your engines oil consumption ?

 

it would not make your fuel dark..

 

The coughing symptom is usually air flow restricted through the turbo and causing a back pressure wave up through the intake system. Black or dark fuel can also be caused from hot fuel going through the head, called asphaltene, and somewhat normal with certain filters and bio-blended fuels.

 

Black fuel could also be from algae. You should get it tested. There are conditioners for that. The coughing can also certainly be fixed as well.