Being a newbie, I've looked through the forum past notes and haven't seen any referring to my situation.

I have a 2001 7.3 L Excursion with a vibration problem and 85,000 miles. Right now the is a slight shudder under heavy acceleration, with a pronounced vibration between 50 and 65 MPH. Vibration goes away when shifted out of overdrive. It's not in the steering wheel. Also, truck is hard idles rough when started cold, and "seems" to have an uneven exhaust stream.The engine also seems to have a vibration in neutral at around 1800 to 2000 RPMs...

The mechanic working on my truck has rebuilt the rear end, replaced the drive shaft with a used one, and replaced both front wheel hubs and 4x4 hubs. I cleaned the EBPS and tube to fix that common cold starting problem - lack of power when cold. There are no trouble codes evident, and it passed a cylinder contribution test that he ran twice. He looked at the transmission flex plate through the inspection port and it looks fine. The vibration is evident when on the road, and he has a dyno that he put it on (just rear wheels running) and it showed the same. It seems to run through the whole truck, exhaust, driveline and engine. My mechanic now now thinks that the problem might be with the injection system, maybe a stuck injector or the oil system that opens the injectors.

Does anyone else have other ideas that we could be looking at?

Thanks,

Exdriver

 

This may not help you all that much, but I had a similar situation on my 2000 Excursion. I was able to hear the problem as well as feel it. What it turned
out to be was the transmission flywheel. It was progressively cracking around the converter bolts - going right across the flywheel. Eventually, the converter would have separated from the flywheel and the truck wouldn't have moved. The noise and vibration got progressively worse. I had a friend at the dealership and we checked it out at night. Since its a diesel, the warrantee was still in tact, so it didn't cost me all the much to have the trans r&r and the flywheel changed. Good luck.

 

Thanks. Were you able to see this crack without removing the transmission?
we hear it too, and almost seems to be in the exhaust.

We thought it might be the torque converter, but after romoving the transmission plan, there isn't any significant metal.

Thanks for the reply!

 

No way were we able to see it by removing the converter shield. As a matter of fact I even took the cover off and looked with a flashlight for quite some time. I started the truck on the lift w/ the cover off - not a chicken, but that scared the heck out of me and we knew it was coming from there. We couldn't tell if the trans was coming apart, if the converter bolts were loose or what. We had to shift the trans back significantly to remove the converter and flywheel. Like I said, my friend at the dealer took it from there.... Good luck

 

Thanks! We see how it goes.

 

My 7.3 had a similar vibration and it was the flywheel also, but mine threw one of the balance weights off.

 

Thanks everyone for the replies. I finally figured out what the problem was. After doing all the work described at the beginning, plus removing the transmission pan to see if there were any metal bits in the filter or pan and a bunch of engine diagnostics, it turns out it was the drive shaft. I gave up and brought the truck to the dealer, one u-joint was bad, and more importantly the drive shaft needed to be indexed. Apparently, my normal mechanic pulled it apart to grease the splines and must not have put it back together in the same orientation. 3 hours of dealer time, and smooth as ever.