Bolting a new axle up?

I think the oil control problem is at least partially from those things running on cold holes a lot of the time. We had a CM870 apart here last year that was pretty much carbon free. But it’s in a train tractor so it gets the balls worked off it most of the time, and it ran 750k of 920k mi with a fixed geometry turbo on it.

 

I think that's part of the problem. A modern 15L is way overkill for typical US weights, even 5 axle weights in Canada aren't enough. You've gotta put them to work and make some heat. Probably part of the reason we're seeing a lot of these newer engines in 12-13L displacements so they get worked hard enough to stay hot.

 

I agree with both these Posts...

 

I am not disagreeing with you guys at all, but the carbon packing issue was because of piston design. Cummins (and every engine manufacturer) was trying to find the easiest solutions to combat emissions in cylinder. At that point, it was well known that unburned HC emissions could be greatly reduced in cylinder if the piston topland volume was reduced. What they didn't discover in the validation process was that the decreased crevice volume would become packed full of carbon that ultimately created a carbon dam that would not allow cylinder pressure to act on compression rings and the carbon also would polish the liner. The solution was APR ring and liner design. Detroit and Paccar had already been using this design in NA with great success. CM870 didn't use this type of piston. Most older engines can be updated to the newer style closed skirt APR style pistons and liners with the brass counterbore captive shims.

 

Yea lugging around like that is allot of pressure on them I don’t care if it 1965 or 2080 + I’ve drove few red Cummins and they will not pull a greasy string out of a cats but at 11 or 1200 and sound like their about to come apart

 

Heard that from a lot of people. Let it drop under 1300 and it falls on its face.

 

The last one was the x15 with all the torque 18 and 390 gears. I heard for months that I would want to do away with all my old motors that was far from true in the lugging range they told me about, if you drove it like an emodel cat it done pretty decent but nothing impressive.

 

I've got a Cummins with a 13 speed and 3.25 rears and I wish it had at least 3.55s. I keep my RPMs above 1400 when running and if I'm heavy I'll split the gear and run higher than that if there's a lot of hills. Truck runs better and MPGs are a little better than when I was running at 1200-1300 RPMs.