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Mrkentee · 01-17-2019, **(Subject: Elusive vibration )**

I have a vibration/shake under a load at around 20 psi boost at around 1300 RPM. If I down shift and bring the RPMs up, it smoothes out. As soon as I let off, it’s gone. Sometimes accelerating up to 28-30 psi boost it’s gone/can’t be felt. Just replaced all 6 injectors due to age, and hoping this might go away. Could this be caused by dirty/worn fuel or timing actuators?
Idles smoothly but shakes a bit at 11-1200 rpm.
Rear motor mounts are one-year-old. Fronts are original.
Crankshaft dampener is about three years old.
Driveline has all been gone through.
933,000 miles.
2010 CM 871

Rawze · 01-17-2019, **(Subject: Elusive vibration )**

May or may not be your troubles but just sharing this...

When mine did that, it was the rear most u-joint on the rear axle. It Would only vibrate at certain boost range in certain rpm range. Felt like something in the engine ... Wife swore it was the turbo, I said clutch or driveline. Told her to have it looked at as she was already on the roads ,.. a week later, this was the result...
http://rawze.com/forums/showthread.php?t...7#pid15827

Mrkentee · 01-17-2019, **(Subject: Elusive vibration )**

(01-17-2019 )Rawze Wrote: May or may not be your troubles but just sharing this...

When mine did that, it was the rear most u-joint on the rear axle. It Would only vibrate at certain boost range in certain rpm range. Felt like something in the engine ... Wife swore it was the turbo, I said clutch or driveline. Told her to have it looked at as she was already on the roads ,.. a week later, this was the result...
http://rawze.com/forums/showthread.php?t...7#pid15827

I definitely remember that. But...I have a new jackshaft, 2 new rear diffs, all new yokes, carrier and balanced (as one piece, not separately). Boy oh boy! I don’t know.

Rawze · 01-17-2019, **(Subject: Elusive vibration )**

at 900+k, has the rod and main bearings, etc. been done? Not likely a cause of vibration your describing, just mentioning it too.

Mrkentee · 01-17-2019, **(Subject: Elusive vibration )**

(01-17-2019 )Rawze Wrote: at 900+k, has the rod and main bearings, etc. been done? Not likely a cause of vibration your describing, just mentioning it too.

Inframed 330.000 miles ago.

Rawze · 01-17-2019, **(Subject: Elusive vibration )**

(01-17-2019 )Mrkentee Wrote:
(01-17-2019 )Rawze Wrote: at 900+k, has the rod and main bearings, etc. been done? Not likely a cause of vibration your describing, just mentioning it too.

Inframed 330.000 miles ago.

Has the overhead valves been adjusted since the inframe?

Mrkentee · 01-17-2019, **(Subject: Elusive vibration )**

(01-17-2019 )Rawze Wrote:
(01-17-2019 )Mrkentee Wrote:
(01-17-2019 )Rawze Wrote: at 900+k, has the rod and main bearings, etc. been done? Not likely a cause of vibration your describing, just mentioning it too.

Inframed 330.000 miles ago.

Has the overhead valves been adjusted since the inframe?

Yes. I just replaced all six injectors because they were all original. And thought maybe it had something to do with this. No change. It does idle a little better

Waterloo · 01-17-2019, **(Subject: Elusive vibration )**

Throw in new Cam and Crank sensors and see if that helps, they are the same part# and inexpensive. Prior to my in frame at Rawze's, mine had similar issues. Sounded like gravel under the floor board but only at certain RPMs. But, I had all of the wrong parts under the hood, along with worn bearings from what looked like a dry start.

Mrkentee · 01-17-2019, **(Subject: Elusive vibration )**

(01-17-2019 )Waterloo Wrote: Throw in new Cam and Crank sensors and see if that helps, they are the same part# and inexpensive. Prior to my in frame at Rawze's, mine had similar issues. Sounded like gravel under the floor board but only at certain RPMs. But, I had all of the wrong parts under the hood, along with worn bearings from what looked like a dry start.

Might be worth a try. I wonder could an unbalanced brake drum cause this, and how would you check it?