Strange noise

[hi8ha]

Hi Guys:

Some strange noise happens when I start the car (MY99 Carrera C2) for the first time in the day. It is like a ratling/clinking noise, last several seconds then desappears and does not do it the rest of the day. As I said it is just when 1st start the car. Seems to come from the back bottom part of the car. Sounds like a pulley when is loose. Any ideas, has anybody experienced the same?

Thanks

Edited January 23, 2007 by hi8ha

[Johnnyceesred]

Hi Guys:

Some strange noise happens when I start the car (MY99 Carrera C2) for the first time in the day. It is like a ratling/clinking noise, last several seconds then desappears and does not do it the rest of the day. As I said it is just when 1st start the car. Seems to come from the back bottom part of the car. Sounds like a pulley when is loose. Any ideas, has anybody experienced the same?

Thanks

Could it be one of the belt tensioner pulleys?

Rgds

John

[hi8ha]

Could be but why would it make the noise only when 1st started and only once?

[Loren]

Could also be a heat shield near one of the mufflers. They make a "tinny" sound and likely move away as soon as they are warm.

[hi8ha]

Thanks Loren. If indeed is that, could it be tighten?

[Loren]

Usually the heat shield just needs to be bent a little further away from the muffler.

It might be good to have someone else start the car while you listen and try to locate the noise.

[slbates]

Usually the heat shield just needs to be bent a little further away from the muffler.

It might be good to have someone else start the car while you listen and try to locate the noise.

Loren may be on to something. It could also be your muffler. I had an internal muffler failure that sounded like crap. I finally found the noise when I banged on it with a rubber hammer. One pair of GHL's later an d no noise. The noise was really bad when cold and only happened once or twice when fully warmed. Thsoe cold starts though can startle you when you hear things like this.

[Loren]

I would think if it were an internal muffler problem (broken weld) it would rattle all the time - but who knows? :rolleyes:

[Izzy]

Sounds pretty normal to me. It depends where the car is the noise could be startling. For example, open area, can't hear it, low ceiling garage with cars next to you, sound louder. It just bounces around. Bot my 99 and 03 do the same thing

[slbates]

Loren, that was what puzzeled me as well. It took me 2 weeks to find the culprit. I had the air box, rear bumper off, checked everything I could find that could possibly be loose. I didn't cut open the old muffler, but the only thing I could deduce was that a weld probably broke on one side of the internal tubing and when it got hot enough it expanded enough to wedge itself in place. I dont think the internals rusted away because when I banged on them nothing came out of the inlet or outlets which is not typical of a rust gutted muffler. The only reason I even hit the muffler was I found a stress crack on the muffler hanger and thought it may have been allowing the muffler to move. I hit the muffler with the rubber tile hammer to see if I could get it move and that how I found the noise. Pure dumb luck.

[1999Porsche911]

You can eliminate a couple of things easily. Make sure A/C is off before starting. Remove serpentine belt before starting. If noise remains, it is not any of the pulleys. Does it make the noise every morning on cold start and then fine for the remainder of the day? If so, and I know this sounds crazy but bear with me: try pulling into your garage, forward and driving the front wheels up on 2 x 6's so the back of the car is substantially lower than the front. Then see if the noise changes the next morning.

Whatever the cause, there should be no rattling or knocking at startup.

Edited January 24, 2007 by 1999Porsche911

[Scouser]

Does it sound like this?

If so it's fairly typical. Albeit it's a bit excessive IMHO in this sound clip. It's not my car, I got this off the forum

somewhere ages ago.

But my car does have this sound sometimes on a cold start in the winter. It goes after about 20 seconds or so. Done that for the past 3 years.

porsche.wav

[Izzy]

Hmm, not quite, that sounds like a "knocking" more than a rattle to me. What I have always heard on mine, even "loaner" cars at the dealer when I pick them up in a cold morning and they park them in a carport, is a metal rattle. closer to a loose piece of metal, thin or hollow rubbing on another at a high frequency. Like two metal shields hitting each other at high frequency, the sound is also higher frequency (with my ear-meter) than the sound file (lower frequency). I did asked once when picking up a loaner, and was reassured that it's "normal". But the air temp is below 50, and the car dead cold. Goes away within 20-30 secs.

I will try the suggestions above with the A/C off this evening, see if it makes a diff.

[hi8ha]

It is a more metalic sound and does not last as long as Scouser's wav file. As Izzy said it is kind of a metal rattle. I would say like a loose pulley and seems to be generated at the lowes part of the engine. Will try to have someone start the car while I watch/listen.

[Scouser]

It is a more metalic sound and does not last as long as Scouser's wav file. As Izzy said it is kind of a metal rattle. I would say like a loose pulley and seems to be generated at the lowes part of the engine. Will try to have someone start the car while I watch/listen.

ANother sound I used to get which was similar to what you describe came from the alternator pulley. The belt was tightened and it went away.

Is there any way you could record the sound and post it so that we can hear it?

[Izzy]

I will work on that, my wife got a new MP3 that has a voice recorder (still in the box) that could work. I am not that tech savvy, still holding on to my 8 -track player.