Clunking Sound at Startup (Brakes?)
 

Hi Guys,

This is my first post. I just bought my grandma's garaged 1996 Olds Ciera. Only has 22k miles. Bought it in Ohio and got new brakes and rotors on it (inside of the pads were worn and rotors were warped), then drove it to PA.

Yesterday, just before I drove it in for the state inspection, I noticed a strange noise. Right at startup, about 1 second after, there was a soft clunky sound coming from just behind the break pedal, as if something was moving into position. It kind of sounded like a stick scraping the back of the firewall. I restarted the car several times and it happened every time. I figured it was brake related after about the 6th time, when I decided to start the car with the brake pedal depressed. No sound at all this time. But as soon as I let go of the bake, there it was again. Just once, and only after startup. I was thinking it was related to the vacuum system and/or brake booster or master cylinder. Brake fluid is full. Components seem clean. And the mechanic said the brakes are fine and that cars just make noises like that.

I'm just wondering if that sounds familiar to anyone out there. It doesn't sound horrible, but it definitely sounds like some parts are moving around, automatically, at start up. And the clunky sound concerns me. It's not a hiss, which I know would be related to the booster. Doesn't sound like air at all. Could there be a membrane inside the booster pump, that's crackling the first time, and first time only, when air rushes in?

Any thoughts would be helpful. Thanks!

Oh, another thing. When I took it in, the mechanic said the right tail light was out, and that a new bulb wouldn't work. Said it was an electrical issue tied to the turn signal switch, which had to be replaced. He replaced it, and now the trunk actually works again! I thought the solenoid/actuator was shot as the key fob and internal button wouldn't activate the trunk, but after the new turn signal switch, it started working again. I wonder if it was just a fuse that was out, for both the trunk and the tail light, and the turn signal switch was even necessary. I suppose I'll never know. Ok, sorry this is two questions/comments. Thanks again.

I suppose you could disconnect and cap off the vacuum line to the brake booster, then start the car and listen for the noise.
With that few miles, and being 15 years old, I wonder if there are any seals that have dried out or gotten hard that are making noise.

thanks!
 

i think i'll try that, and keep an ear on it from now on, to see if it gets any worse.

I think your right that there is something wrong with your brakes and I don't know why your mechanic said that. Noises like that is of course not common. I think your problem is like what happened to me last month and I ended up buying new zimmerman brakes and the noise is gone. Good luck

brake noise
 

if your car has abs it will sometimes perform on board test up to 12 mph i believe had same noise on my 95 88.