Knocking and Vibrating 2005 W900 Cummins 400hp ISX

Could be a bad cabmount or motor mount.

 

"it will also knock or vibrate against the floor board when under a load or pulling a hill"

My Pete will do this if the clutch is adjusted too high, when the truck twists up from the torque the clutch will loose any freeplay and top out making vibrations in the floorboards and noise.

 

yo tengo un kwT2000 ""06 cummins 400 ISX con 573000 millas pero este motor cuando lo compre en el dealer me dijeron que lo habian abierto a 500 hp....so modificaron una valvula del turbo y no se cuantas cosas mas, pero tiene ese mismo sonido que tu camion, le dije a mi mecanico que se subiera al camion y lo manejara y escucho el ruido y me dijo que cuando el turbo se llena de aire y ya no necesita lo regresa al filtro de aire y lo expulsa por halli....debido a la modificacion._yo la verdad ya llevo con mi camion 3 meses con el mismo ruido pero no hay ninguna diferencia de fuerza....El mecanico me dijo que no me preocupe por el ruido ya que nada malo le va a pasar al camion, ya que si no quiero escuchar el ruido tendria que modificarlo otra vez a su estado original....cosa que no voy a hacer......espero te sirva mi comentario y disculpa que no lo hice en ingles pero yo no puedo escribir mucho en ingles y no quiero confundirte....Me gustaria saber cuantas millas por galon deberia de hacer este motor cummins....gracias.

 

Agreed, my W9 with a C15 did that for about two weeks while I searched everywhere for the issue. Found it running down the highway and putting my foot under the peddle and pulling up. Noise went away immediately so I had the clutch adjusted back into spec and it's gone.

 

My 2001 T800 vibrates also when idling. The needle on my rpm gauge will slightly move back and forth and when laying in the bunk it feels like I am in a 70's cheap motel room with a vibrating bed. It doesn't do this at first when I start the truck up but will do this later in the day. Nobody can figure out what is wrong. I have had the overhead ran and everything has checked out good. But you can see the motor shake when it does it and put your hand on the truck and fill it.

 

my volvo does just the same, did you figure out the cause ?

 

Mine did that til I replaced the cab bushings.

 

Nice...now I need a "Rossetta Stone" to read my computer.

 

I'm getting the same symptoms. Unstable Engine Speed, engine knock (internal) when pulling hills in the powerband. You can hear a rumble in the exhaust at idle (aside from the normal clean, smooth exhaust note) and see the tach surging 100 rpm.

Things we've tried:

1. Rebuilt the engine 7k miles ago
2. New cam, and 1 new rocker
3. New timing actuator
4. New exhaust gas pressure sensor
5. New turbo and turbo actuator
6. 2 gallons of lucas
7. New CAC
8. New Radiator

It's a CM870 (ISX 475 EGR).

With what sounds to be a fuel knock, and the unstable engine speed, I am leaning toward it being in the fuel system. Maybe sucking air, or an injector going bad. Poor power, and fuel economy really suffering. It also occasionally throws a code for "Power imbalance detected between cylinders". So I am going back to cummins tomorrow and hope they can fix it. I'll have them run a power balance test to see if any injectors are putting out more than 100% suggesting a leaking injector neighbor.

Any other ideas on what to have them check? Fuel pressure, and presence of air bubbles probably, eh?