Whats up everyone. Asides from my constant CEL thanks to my de-cat downpipe, my first "real" problem has arisen with the balt. I have an '07 2.4SS w/ about 22k on it. The other day, I noticed a knocking noise that occurs when I brake. It starts knocking (noise appears to be coming from the front of the car) when I get under maybe 15mph or so and knocks right up until I come to a complete stop. The knocks are evenly spaced and it isn't that loud, but is def noticeable. Nothing seems to be noticeably wrong though.......the car still brakes, turns, stops, goes and everything in between, but the noise is annoying and I want to get whatever it is resolved and figured out before it turns into a REAL problem. Anyone else experience this?

 

Check your CV shafts first... Also make sure you dont have a flat spot on one of your tires either..

 

I dont have any flat spots on my tires. The car dosent vibrate while I drive and all.........it only makes the knocking noise when im slowing down, and sometimes when I first start rolling from a stop.

I did check my Ingalls ETD, and its def not that. I know that makes some knocking noises when its super cold out, but this knocking noise is being made in like 95 degree weather.

Where are the CV shafts and what should I be looking for once I find them to spot a problem?

Thanks.

 

The cv shafts or axle shafts protrude outward from the differential to each of your front wheels. A quick check would be to look at the boots where it is attached to both the differential and the wheel. It is #8 and #12 in this picture. You need to check to see if there is any noticeable oil leak or if the seal is torn even slightly:

[IMG][/IMG]

 

I dont believe its leaking any oil. Motor oil?

 

It will be a pretty thick grease. But will still give that oily/greasy wet look so part of the boot if it's ripped or torn.

extreme case:

 

alright, thanks.

 

Just an FYI, Even if it doesnt leak doesnt mean its not bad, it will only leak if the boot is broken, doesnt mean there not bad... just an FYI...

 

True. Most of the ones that get replaced where I work (GM dealership) they are not leaking. There's no visible signs of wear or fault.

 

well, i've been driving around with this noise for a little under a week now. If it is in fact the CV shaft/joint, is it safe to be driving it around. I haven't had any real trouble with it yet. The car seems somewhat unstable (bobs around more than it used to), but it hasnt really affected my daily commute. I have an appt with the dealership on Thur, and its my only car, so I kinda have to drive it. Is this safe? lol

 

Well, the problem with bad CV joints is that it can have an effect on your entire transmission because you need everything working in unison. I told this to one of my friends the other day who has an Accord; his CV joints went bad and I warned him that he needed it fixed. He didn't and ended up with alot more damage than you would expect.

I would say, if you have an appointment on thursday you'll be fine. Just don't drive it hard AT ALL and you'll be cool.

Oh yeah, and like they said, even if the boot isn't torn or shows signs of leaking, that does not mean it isn't bad. It's just a quick check you can do without really messing with anything.

 

what octane gas are you using? you should be using octane 91, I had a similar problem, once i switched from 87 to 91 it stopped. it also says something about a knocking noise in your car manual.

 

I had this same issue on a different kind of vehicle. Turned out the front brake rotors were warped from heat. This was on a PT Cruiser though. Same symptoms you describe though. Dealership tried to blame my aftermarket racing wheels for letting the rotors cool off too fast thus warping them but I called BS on them and they warranteed the rotors and told me to have a nice day.

 

I use 93, and I have since I took the car off the lot brand new. I assure you its nothing engine related.

I checked the CV boots and they appear to be fine. But im gonna take it in tommorrow and let them take a look.

 

yo whitess...i had the same problem with my 2.2 when i had it..at times ihave it with my 2.4ss. its the rotors. they warp very easily..they pretty much blow. i had the dealership replace them.

 

At 22k I would suspect it isn't very serious or maybe it is. A serious knocking noise can be many things. If it is occuring when you brake it is likely something in your frontend. My wheel was knocking and vibrating and you know what...... it was about to fall off:
https://www.cobaltss.net/forums/general-cobalt-68/wheel-theft-worse-63610/

Check your control arms and wheel axles as someone else has said. I would have the entire frontend checked out at the dealership.

 

well, I figured it out guys.........your gonna LOVE this one!

My friend suggested something verrrrrrrrrry simple. He said that a while back, one or two of his lugnuts on his front wheel were lose, causing the wheel to be unstable and knock up against the caliper when he braked. So I said "well lets check them and tighten them if needed". Well, the front left wheel was fine, everything was still pretty much 100% tightened. But the front right wheel...........it didnt take us long to figure out the problem and start laughing. Turns out not one........but TWO of my lugnuts somehow managed to free themselves, lol. And they happened to be next to each other on the wheel, so the wheel was very unbalanced. We did move one of the lugnuts to the opposite side of the wheel to better balance it for the time being. Im gonna hit up Autozone for a new set of lugnuts and perform the simple fix, but for now, the 3 lugnuts holding the wheel on seem to be fine for the moment. My friend drove his Cavalier around with 3 lugnuts for nearly a year with no problems, so I think i'll be fine until I get some new ones, lol.

Thanks for all the help anyways!!