Mechanic willing to help

I know this is a silly one to bring up because I'm sure its been checked. Do you have wheel balancers?? Sometimes they do fail...not much but they do. All the weight will stick to one side.

Some drums will also slide slightly one way or the other if not watched while mounting tires. We have 4 KW's with drums like this on our steers.

Also I know you say they checked your driveline. Do you have full round or half round yokes?? If half round check for lateral movement. Sometimes you have to really get ROUGH with them and even jack the rear of the truck up so you can take the psi off the driveline. The half round yoke ears can have just enough side to side play to cause vibration but its normally when you let off.

Just a few things that pop into my mind...

Vibrations and non code electrical issues are the worst to diagnose sometimes.

 

+1 on carrier bearing. I've seen many with excellent bearings but the rubber is shot. As stated, get rough with it, only good way to find it. Also might take a grease gun. Grease every u-joint...not for grease per say...to make sure that ALL 4 are squirting grease. If one of the 4 is not...you may have a bad cap of flat needles due to lack of grease...but it still feel tight.

 

Please enlighten us on what you mean by operator error?

 

not as bad when bobtailing, It vibrates sitting still parked, but vibrates more the harder you work it (hills, heavy load, strong wind). all u joints steady bearing has been checked and double checked, disc brakes on all axles, rotors have been checked, No wheel balancers and tried different rims and tires. Thanks for ideas, keep them coming as it has everyone here scratching their heads.

 

Did you mention overhead being run?? I'm sure they did when they installed the two injectors. Are we sure it was a good job? Do you trust it? The reason I say this is I've seen overheads done in a hurry that might have not had the time taken that they should've and the truck ended up running as rough or rougher after leaving the shop.

Could it possibly be the harmonic balancer? Maybe a Fan hub or idler bearing??...I know, I know not hardly possible but crazier things have happened. lol. Have you checked bellhousing for cracks? Just some more thoughts. Keep us posted!