Vibration question...

[OrngK5]

Hey guru's, quick question for you all. I searched the forum earlier for some answers to a problem with my 1978 K5 400cid th350 having a small vibration upon acceleration that can be felt through the gas pedal, steering wheel and cab. The engine sounds like it is running smoothly, no loss of power but some of the answers pointed to possible U-Joint failure.

I put the truck in neutral, removing the load, and applied the parking brake and checked the rear drive shaft off the transfer case, NP203 with adapter, then checked the connection between the drive shaft and rear differential. I was able to spin the drive shaft a bit but there was no up and down "play" in the shaft. This morning when I was reversing out, there was a "tick" noise but I wasn't able to really locate where it was coming from and haven't heard it at all while doing some errands.

Overall the truck is stock, shocks were replaced 3,000 miles ago with Bilsteins. Could it possibly be a dead cylinder? Thanks for your help!!

 

[ryoken]

my money's on the u-joints... most of the time they wont have play when you first start getting the vibe, and when they get play, they're really fubared at that point.. if you don't know their history, do em, it's piece of mind maintenance....

 

[OrngK5]

Thanks for your help! I honestly don't know the history of the U-Joints but from the original owner, he said he rarely drove it and supplied documentation to prove it. Now that I've owned it since Oct 08' I have put 3,000+ on it but has driven fine since I got it. Is there anything else I should look for or notice to diagnose it more towards U-Joint opposed to something else, i.e. cylinders, tranny or transfer case?

 

[4X4HIGH]

Might sound stupid but with the truck stopped and the engine running do you feel any vibration then or is it only when you're moving?

 

[OrngK5]

Might sound stupid but with the truck stopped and the engine running do you feel any vibration then or is it only when you're moving?

I feel some, it's worse in lower speeds while accelerating but noticeable while cruising around 45-50mph. Also there is a high sounding whistling noise while accelerating too, I'm not sure if it is related or not.

 

[4X4HIGH]

I'm still not sure if you feel vibration with the engine running while NOT moving. If you do feel any vibration with the engine running and the truck NOT moving then the vibration is obviously coming from the engine and not the drivetrain. A vibration while driving could be a driveline issue or even a wheel balance issue.

 

[OrngK5]

I'm still not sure if you feel vibration with the engine running while NOT moving. If you do feel any vibration with the engine running and the truck NOT moving then the vibration is obviously coming from the engine and not the drivetrain. A vibration while driving could be a driveline issue or even a wheel balance issue.

Thanks for the tip, I'll go get the tires rotated / balanced see if that helps.