Hey everyone, I need help diagnosing a problem on my sisters 2000 GMC Envoy. At speeds above 20 mph, there's a strange vibration that I cant pinpoint. Its loudest at around 45mph. Here's the kicker. Its not a constant vibration! It's intermittent. The vibration fades in and out every 4-5 seconds, and lasts about 3 seconds. At first I thought maybe wheel bearing or U-Joint, but usually those produce a constant vibration and/or noise. Its got *drum roll* 268k miles, if it helps. I'd really like to figure this out asap. Thanks in advance!

 

Is it in 4wd?

 

No lol

 

It could be a u-joint, or possibly the front axle disconnect isn't disconnecting. The front driveshaft should spin while its in 2wd.

 

i would double check all the U-joints in the front and the rear. could it also be a wheel weight perhaps?? or an aging tire that needs to be changed????
just my .02

 

if the vibration can be felt in the steering wheel try rotating the front tires to the back of the truck and see if it goes away. might just be a bad tire

 

All very good suggestions. I'll check all of that out and get back to you guys.

 

That sounds just like what my truck did when my tire had busted bands. Not sure if there's a technical term for that or not.

 

That's interesting. I'm not sure how old the tires are, but still worth checking. Thanks.