I recently purchased an 08 silverado, it had 11,996 miles on it, and it was sitting at the car lot for around a year-year and a half. I have put ~ 700 miles on it in a week and a half, and purchased new tires for it yesterday as the old ones were dry-rotting. Anyway I put around 130 miles on it last night, went home, then had to go back out to the store. During the 130 miles I had no issue what so ever (over 80 of which was with the new tires) untill I left for the store. I was pulling out of my road, and got up to around 20 mph, and I felt a jerk. It felt like someone jumped in the bed of the truck or something. I actually stopped and turned on the bed lights to see if anything was back there. Well nothing was there, so I kept going. About 15 seconds later, THUNK! I can feel the jarring from it throughout the cab of the truck. It almost feels like it is the driver side brake randomly locking up for a split second.

I was at advanced auto a few days back asking about a steering column issue making a squeak when it gets down below freezing, but I also discussed a noise I had heard from the rear of the truck (only heard it 2-3 times on a 20 degree morning so I'm guessing it was just cold) and bearings were brought up. The guy said that bearings can go bad if you leave a vehicle sitting for as long as my truck was sitting. Anything I have googled about a thunking noise has brought up bearing related things (bearings and a thunking sound silverado's tend to make when turning, but this happens when I am going straight too).


But yeah it actually jerks me forward a bit when it happens, then it's gone, and comes back 15-20 seconds later. I am going on a 900-1k mile trip on wednesday, and need this resolved before I leave, so any help would be great.

The easiest way to check wheel bearings is to jack each wheel up individually and physically take the wheel in your hands and try to move it. If there is any movement in the hub, its a bearing.

Thats where id start. Id also take a few minutes to inspect the tires as they could have a flat spot from sitting.

I kind of doubt its a wheel bearing though....the symptoms don't add up.

from my experience with bad wheel bearings it might start getting loud when you drive down the road because the bearing is wore out and also ive seen them when you take a turn start popping and stuff. do like andy said and jack it up and try to move each wheel. if you suspect a bad bearing you can sometimes visually inspect one from the backside of the wheel if its faliing apart.

Alright I will try that tommorow. After 50 miles today, it started right before I got home (on the same road oddly enough, but it just started doing it). It only happens at lower speed (18-25 mph). It didn't jerk as hard this time though. The ride is smooth, and as far as I can tell there are no flat spots in the tires. The steering wheel has no jerkiness to it, so idk if it is an issue with the steering stuff.

This post was edited by skyeye on Dec 16 2012 08:23pm

uhhhhh Question:
Is it a 4x4?

Nope but I think I figured out what the problem is related to. I was sitting in the truck in my grandparents driveway and it started randomly making the clunking noise. My grandpa told me to pop the hood, and we watched the engine when it happened. It does it when the clutch or w/e for the air conditioning starts spinning. We sat there for 5 mins and it didn't do it once, turned the air on CLUNK! The air blows fine and stuff, but it doesn't explain the jerking (which occurs at the exact same time). Maybe I just hit a bad spot on the road at the exact time it clunked that first time, but w/e the issue is it is DEFINITELY related to the ac being on.

Had one of these go out on my mother's Ford Taurus.... It chewed the belt up in about 30 seconds. I'd recommend having it serviced asap. The potential damage caused by not having the belt is almost as bad as having to shopvac bits of rubber out of EVERYTHING. lol

Any idea where it would need to be serviced at? I noticed a squealing that I THOUGHT sounded like a belt, so that would make sense. Since it is an 08 idt it would not be covered under a 1 year dealers warranty, but idk if it would be covered under car-max's 100k mile warranty. Sorry I am new to the whole getting vehicles worked on thing, as I have only been driving for this week and a half-2 weeks, and idt going to the jiffy lube is the correct place And I'd like to add that when you are outside the truck looking at the engine you don't hear the clunk, you just hear the clutch engage and the motor revs slightly, but inside the cab it is fairly loud, and going by what other people have said it sounds like someone hitting the frame with a rubber mallet.

This post was edited by skyeye on Dec 18 2012 06:29am

Ya it sounds like either the clutch or the bearings in the A/C are going out. I would highly suggest not going anywhere near jiffy lube though lol. Not sure what all you have for automotive shops out there but I would try to do some research online and find a place that is a little more experienced and has decent reviews. Btw it doesnt hurt to get a 2nd estimate of course.

Take it to a shop and stop fucking around.