X15 noise and lack of power on a hard pull.

[marek4792]

Cummins/Eaton do program their engines for low rpm but the problem is that Cummins didn't design it for low rpm like Paccar and even Volvo has!! Cummins engines have a mid stop liner design that is very notorious for fretting and blowing head gaskets due to low rpm high torque operation. Also I know Texas has got big speed limits and even I and some of us here like driving fast too but I'd back it down to 75 due to tire ratings if you gotta go fast but slower the better is the game here. Does the noise follow road speed or engine speed? Did you change tires recently are they mounted/balanced properly? Any vibrations when it "misses"? What's your average fuel economy? What terrain and equipment do you run? Sounds like you got 3.08s for rears? Usually you don't see that tall of gear unless it's a direct drive transmission like Paccar and Volvo which usually run 2.64 gears and that tall of rears paired with an overdrive trans is very detrimental to performance, fuel economy and your liners in high demand situations. What you have is a very poorly spec'd truck that is destined for failure!