Mysterious Car noise - fixed

[easysurfer]

Things often are what they seem to be. I had this mysterious rattle noise when I'd go over a bump in the car. Not always, but sometimes. The noise sounded like it came from under the left back tire area.

So, I brought my car in to my local friendly Car-X repair shop. At first, they thought it was a hook that hung the muffler. So, they added some welding. But after I test drove it, I could still hear the noise. Then I test drove the car with a Car-X employee inside, to my surprise..no noise. (No charge for the welding).

Took the car back, then drove it and of course, the noise reappeared. So I brought it back to the next day. After they test drove it and finally did hear the noise, they found out the culprit was an old rusted battery bolt. When I'd hit a bump, the bolt would clank. I could have sworn the sound was coming from the rear left..but instead, was apparently the front left.

Anyhow, all is well now. Nothing like process of elimination to troubleshoot.

 

[travelover]

I worked in the noise and vibration end of the car biz and squeaks and rattles were part of it. It is amazingly hard to tell where a noise is coming from. We had a special machine (4 post shaker) that independently bounced each wheel and allowed you to walk around and under the vehicle to find issues. This machine was also in a climate controlled room because some problems were only there when hot or cold, or humid.

I don't miss it.

 

[powerplay]

Happy to hear you resolved the problem. As I started reading the thread I thought it might turn out to be something in the trunk bouncing around making the noise.

 

[easysurfer]

Happy to hear you resolved the problem. As I started reading the thread I thought it might turn out to be something in the trunk bouncing around making the noise.

That was my very first thought as I had this small hand truck in the trunk and initially thought this was bouncing around. The when I took this out and the sound persisted was when I first said, this is not an inside the trunk issue.

 

[TromboneAl]

A mystery that took me years to solve was a bad smell that occurred infrequently. It turned out that I had used a milk jug to mix the windshield washer fluid. If I used the washer when the heat was on, the sour milk rotten odor was drawn into the car through the vents.

 

[HawkeyeNFO]

One time we had a rental minivan at Lake Tahoe. A big boulder had fallen on to the road ahead, and by the time the driver saw it, he was unable to stop in time. In the other lane there was oncoming traffic, so he couldn't get out of the way either. So he ran it over, and it was about 9-12 inches high. We hit it head-on, and it certainly hit some mechanical parts on the bottom of the car. luckily it still worked, but it made some of the worst noises ever.

Then we figured that someone had turned off the radio, and that was why we heard noises. Once the radio was back on, the noises disappeared, so you just had to leave the volume up. A day later, we turned in the van and never worried about it again!

 

[JakeBrake]

Recently, I had an annoying metallic rattle under my car. I took the car to my mechanic to listen. He said I needed a new catalytic converter. He recommended a nearby independent muffler shop. I drove to the muffler shop. The shop owner happened to be standing out front when I arrived. Before I had a chance to say anything, he said "you need a catalytic converter." He replaced the converter and the rattle was gone and performance improved. The car is a 1998 Chevrolet Cavalier with 173,000 miles, So, I suppose it was time for a new catalytic converter. He said the original muffler and exhaust pipe were fine.

We don't have emissions testing here. My guess is I would have flunked an emissions test long before the catalytic converter rattled.

 

[TromboneAl]

On a surfing trip with a soft rack, I would get a loud buzzing at some speeds. It was too loud to tolerate, and I tried many things, like tying towels onto the straps, to fix it.

Finally I had someone else drive while I stuck my head out the window and watched. What was happening was that the board was lifting the pads off the roof, and a strap under the pad was vibrating.