Vibration at 50mph top gear 6.0l

[Seaportsteve]

Hello, my 6.0l powerstroke seems to have a miss fire, ir runs ok and has no smoke from the exhaust. When i get up to 50mph and it goes into top gear i get a vibration when putting my foot on the gas. I can push the tow button and the gear shifts up and vibration gone or put my foot down where it kicks down a gear and ok again. If i get up to 70 and it goes into top gear the i get no vibration.
Truck is not as responsive due to mis fire but still drives .
Truck is in the U.K. and our mechanics just re not interested in trying to fault find. an anyone help please ?
Thanks Steve

[late_99_PSD]

Does it seem like an engine vibration or more of a driveline vibration. I would think if it was an engine vibration it would do it in any gear, even if it was parked. What you describe more sounds like a U-joint.

[Seaportsteve]

I get steering wheel movement and quite serious vibration under my feet, it feels front end.Would it be possible that at a certain r.p.m. and a certain gear the vibration is amplified ? I got it back yesterday from a local garage and they replaced the prop shaft centre bearing.
Still same problem and it cost me £ 3k for the priviledge of them working on it.

[late_99_PSD]

3k for a carrier bearing!!!!!! I don't know the exhange rate but thats sounds rediculous.


If it feels like it is in the front end then it might be a wheel out of balance, wheel bearing, or maybe the front universals if you hubs are locked in.

[ibby10]

i had similiar problem, it was bad injectors. had them replaced, runs great now. mine is a 6.0, 2004 . have replaced 7 so far.