CM871 suddenly started using oil

What is a CM871?

 

Bobby this thread might be helpful to you:

http://www.thetruckersreport.com/tr...3-cummins-isx-cm871-technical-discussion.html

KH

 

I don't know why people can't just simplify and say what the engine is in the subject thread, then go more advanced.

 

CM871 basically just refers to what EPA requirements are on it. CM570 is pre-EGR, CM870 is EGR, CM871 is EGR and Aftertreatment, CM2250 is EGR, Aftertreatment and SCR. I'm sure there is more to it but at its simplest form thats it.

Loss of oil without signs of external leaks can be very time consuming. Something that may give you a decent in sight to the possibilities is to have a dealer or cummins hook up to the ECM and review the "Aftertreament History". The ECM saves the last 10 regens, and what they can do is look at the time stamp on the regens and find out how long the unit is going between regens. I'm not 100% sure on the gap between regens but the ECM will automatically initiate a regen after 96 hours ECM time (I believe that is still correct). So if you were to build a table 96 hours would be perfect and the closer you get to 1 hour would be the worst. Now if you are in the "Below 20 hrs" range between regens then liner scuffing could likely be in play. This is not a definate answer but is where I like to start when trying to gauge problems in the engine. Now someone has mentioned earlier about valve stem seals and I agree that would be something to check IF AND ONLY IF ALL OTHER EXTERNAL LEAKS AND POSSIBILITY OF LEAK IN TO COOLING SYSTEM, AND FUEL SYSTEM (fuel system is highly unlikely) have been verified. i only say that because once you start looking internally you start talking about major tear downs. So in order of checks:
1. Externally
2. Exhaust of Turbo
3. Compressor side of Turbo
4. Oil from Air Compressor
5. Oil in Coolant
6. Oil in Fuel (again highly unlikely)
Once all these have been verified
7. Valve stem seals
8. Liner scuffing

Unfortunately I've seen more liner scuffing issues than anyone wants to admit to. Also a simple blowby test more times than not will NOT show oil consumption. The only way to verify is to remove the pistons and inspect the liners. What happens is the rings make smoothe shiney spots on the liners but still keep good compression in the cylinders and thats why a blowby test does not disprove liner scuffing. The quick change is oil consumption can be skewed due to the possible change of duty cycles maybe your drivers dont have identical routes as the previous owners.

 

Make sure the injectors get replaced. We have had a few cases like this and found the injectors to be over fueling, or the spray pattern is bad causing fuel build up on the liner wall which burns into carbon which gets packed into the rings which leads to the polishing. I also recommend that all 6 six liners packs get replaced to keep everything even and balanced. Don't be surprised if warranty only pays for the two they found bad. You may have to pay out of pocket for some parts, but the labor should be basically free since everything is apart anyway.

 

Yes, warranty jobs like this can be very frustration for the person who owns and operates the truck because they end up being the 3rd person in the deal. In the relationship between repair shop and customer, you get pushed out of the loop sometimes, because since Cummins is paying the bill, they are in fact the customer, not you. Hopefully the repair shop treats you right. Just keep on them.