Engine / tranny vibration

[JTodd]

I have a very strange vibration / growling from an unknown source when on the throttle, even lightly. It generally starts at around 1500 rpm up to maybe 2500 (although I rarely see this high). Only happens in gear, any gear. The vibrations are enough to cause at least the driver's side mirror to vibrate (oddly, the passenger side mirror does not vibrate as much) as well as being very noticeable in the seat. The growling / vibration are of a lower frequency. Some possible causes that I have considered:

U-joints - They were replaced recently (1.5 years) and no noticeable play
Injectors - Other than the vibration, truck starts and runs fine. Fuel mileage is high, pulls fine, no noticeable performance degradation.
Front-drive shafts - I also have a metal on metal grinding when going into 4-hi or lo. This has been going on longer than the vibration. I have checked the outer transfer case bearings, and they don't have play, but I have not removed them to check.
Harmonic Balancer - have not checked but that will be next. How is this checked?
Crank Pulley as mentioned by Ronniejoe here:http://thedieselpageforums.com/tdpfo...66&postcount=4 How is this checked?

After that, I am out of ideas, other than something with the transmission such as a bad torque converter or a carrier bearing.

[76m880]

sounds to me like it could possibly be a flex plate

[ttpost]

Or a loose torque converter

[Hubert]

Maybe check transmission rear mount.

[JohnC]

Exhaust touching anything...

[JTodd]

Maybe check transmission rear mount.

The transmission mount seems to be fine - looks solid and complete. No noticeable movement when tail is pushed.

Exhaust touching anything...

Everything looks secure and where it should be, front to back.

How can I check the flex plate and / or torque converter without pulling the transmission?

[ttpost]

just pull off the inspection cover and look at witha a flashlight, its real easy gl rob

[JTodd]

I started to pull the inspection cover to see what I can see. It looks like I will need to pull the cross-over first. It would not squeeze out, even with the transfer case input shaft moved. Anyway, I did get the cover moved enough to get my hand in to wiggle the torque converter. It seem solid, but I noticed something very interesting. In the last 20 hours I have driven approx 15 minutes covering maybe 2 miles running some errands this morning, almost 7 1/2 hours ago and the torque converter was very warm to the touch. The transmission pan was cool, and everything else around was cool, but the torque converter and the flex plate were definitely warm bordering on hot.

Is this normal?

When I have a little more time I will pull the cross-over and have a much closer look in there, probably tomorrow evening.

[JTodd]

I forgot to mention that the torque converter does appear to be engaging.

[JTodd]

to close this out, it looks like I found the problem. I had previously checked the u-joints and they seemed tight and fine. While under checking the transmission, etc, I decided to pull the drive shaft and have a closer look. Although they had grease fittings, it was not going into all four pivots. In fact on the problem joint it appeared that it had never gone into one of them. When checking them while still under the truck, there was enough bind that they felt tight but once relieved of the pressure that one pivot obviously was a problem.

After replacing the front u-joint the vibration has reduced significantly.