Okay, I have a problem that I hope someone can help me with here. Cummins Nt855 was using a ton of oil. like a gallon every day. Started seeing oil in the exhaust. Pulled turbo and exhaust manifold and had oil leaking from #1 cylinder exhaust port. After examining it, I could see that the valve seal on the ex. valve was gone. replaced the #1,#2 head, put it all back together and it it did great for about a week. now it is leaking again through#1 and looked like oil had been splashing back into#2, but dry on the inside. Talked to a cummins tech and he said it could be an injector. so I swapped the #1 and #2 injector. now they are both leaking pretty bad. So now to my question. I do not have a lot of experience with SCT top stop setups, but is it possible that injectors could do this? There is no oil in the fuel or antifreeze. Just coming through the exhaust ports. I thought maybe rings, but why would I get leaking from #2 when I swapped injectors? I plan to check the compression, but had to order a compression checker that would work on this engine and it will not be here for a few days. I am in a very remote area, so cannot just go get one. so in the meantime, I was hoping that someone could give me some information on whether or not it is even possible that this is an injector or o-ring problem so I can pursue other avenues while I wait for compression tester. when I had the head off, the cylinder wall looked great (I know it is hard to tell for sure just by looking)but no scoring in the wall, no oil around the edge of the piston. the oil was right on the top of the piston. and what has me more confused than anything is how it started from #2 after I swapped injectors. Thanks in advance, Trav
pull all you injectors and have them tested. a bad injector can wash down the cyls and thin out the oil.
Cracked piston would be my first guess if there is a lot of blowby.
Anytime i have seen slobber out exhaust it usually is from a bad injector or oil getting by the rings. Is there a lot of blowby compared to normal? How is the exhaust coming out of stack white bluish etc. Good luck.
I pulled the exhaust and could see oil coming out of the ports. Bluish exhaust. I pressure tested and did a leak down test. The pressure test showed good across all cylinders. The leakdown test showed 6 to 8 % is all, and could not hear any leaking. I pulled all of the injectors and found some bad o-rings and decided to change them all. changed injectors and ran overhead, started the truck and still oil coming from exhaust. I ran it for a bit several times and cleaned the old oil out, but it just keeps coming. I am at a loss. If it was rings or a cracked piston, why so good on the leakdown?? I am assuming that I am in for a rebuild, but just want to cross all my T's and dot my I's. Any further input would be great. Thanks, Trav