2001 c-15 vibratation

2001 c-15 vibratation
Posted: Sun Dec 7, 2008 9:45:33 PM

I have a 2001 pre egr c15 in a auto haul set up.  I have a fine vibratation at idle that gets worse at acceleration when pulling a load.  I'll describe it as a harmonic vibe, that I feel in the steering wheel, floor and shifter.  The vibe, becomes really strong through the low end rpm of each gear.  I get the best torque at 1200 to 1400, that is when the vibe is bad.  After I drive through that area I'm fine.   After 4 shops and 2 dyno tests this is what has been done so far.  (Oh the truck has 625000 miles and has been trouble free up to now. )  I have replaced the entire clutch assembly, had the rear ends torn down and inspected including the drive line and joints and bearings.  I have replaced the fan clutch and the turbo.  I just replaced the injectors and was told the top end looked great.  I do not as far as i can tell have any smoke from the exhaust( the exhaust dumps out in front of the drives-weed burner style)   I do not use any coolant .  The truck is not throwing any codes and the dyno results look great.  I have had all 4 shops tell me that the motor mounts look fine.  I also replaced all the supply side fuel lines,primary fuel filter mount and have only used cat filters since day 1.  Any Ideas on this?  I would greatly love the input.  Thank you.

RE:2001 c-15 vibratation
Posted: Mon Dec 8, 2008 10:10:13 AM

Injector with a bad tip causing miss fire at low rpm? You also said it felt harmonic, How about the harmonic balancer?

RE:2001 c-15 vibratation
Posted: Thu Dec 11, 2008 2:34:44 PM

Check that Crankshaft positioning scensor on your truck also.

RE:2001 c-15 vibratation
Posted: Mon Dec 15, 2008 5:19:34 PM

check harmonic balancer for stress cracks,with that mileage-who knows,,,let me know