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+--- Thread: Cm870 oil loss (/showthread.php?tid=10806)
Cm870 oil loss - Nwttrucking - 11-02-2026
New to me truck with 2006 cm870 didn't appear to have any blow by. Ended up needing a turbo which was just replaced. Drove it 3 hours under load and it lost over a gallon of oil just in 3 hours. No smoke that I could see. Turbo looks dry on both ends. No idea where a gallon of oil could have went that fast unless it's just burning it like crazy
RE: Cm870 oil loss - mikkhh - 11-02-2026
What turbo was the replacement one?
New genuine? Cummins reman?
Some chinese junk that is faulty straight out the box?
How and why the turbo was deemed culprit?
RE: Cm870 oil loss - Rawze - 11-02-2026
maybe whoever did the replacement turbo did not bother to top it off properly?.
if its burning that much, the exhaust would have white plumes.
Is there excess smoke coming out of the blo-by tube?.
It is wet with oil all over the turbo or areas where someone worked on it?.
It either was missing, or it had to go somewhere.
RE: Cm870 oil loss - Nwttrucking - 11-02-2026
Cummins reman.
Checked oil after turbo was replaced. Hauled 3 loads of rock and checked it again and it was a gallon low. Couple drops out of the breather tuber from sitting over night. Limited blow by. Couldn't see any smoke when it was loaded, but empty theres maybe slight haze of blackish smoke when flooring it for a sec, but pretty normal for just fuel being burnt. Turbo was dry all over just typical soot on the exhaust side. Fuel tank is clean, coolant is clean, air dryer clean. Curious if an oil ring got stuck or broke. Ran the truck to a shop for 45 mins and it didn't lose a drop of oil, so my guess is it only happens under load. Truck is doing a silent derate to 20psi max boost with no lights coming on, but I believe thats a seperate issue because the shop left a huge leak at a v band clamp on the egr, or possibly some sensor failing? A gallon in 3 hours I would think would have left some sort of wet residue coming out of the turbo, but it looks dry.
RE: Cm870 oil loss - Andre_The_Giant - 11-04-2026
How are you reading boost pressure? Is it a glow shift boost gauge? Those have been known for being over tightened when installed and saying around 20psi when you actually making 30
RE: Cm870 oil loss - Andre_The_Giant - 11-05-2026
You might have mor blow by then you think. Dont check for it at cold idle, get a load on and go pull a long hill at operating temp, pull over on top and check breather & oil fill port. I’ve ran an 870 for 10years now and smoke usually ends up being egr valve starting to stick
RE: Cm870 oil loss - 3406E - 11-05-2026
Over a gallon in 3 hours is a lot to not see where it’s going. My cm870 once dumped 3 gallons of oil through the blow-by tube when the piston rings went out and the oil painted the undercarriage straight to the rear of the truck. This is the fishiest oil leak I’ve heard of, I’m kinda puzzled