Strange exhaust noise when engine is hot

[dcporsche99]

Hey Compass1,

I had two areas of vibration similar to the one that you described. For the first one, I ended up putting a large screw-type hose clamp completely around the heatshield (re: after having tightened all possibilities to no avail) and that was able to do the trick.

The second vibration came from an aftermarket header that was abutting the variocam cover w/c I was able to creatively muffle using exhaust wrap and two screw-type hose clamps.

Good luck and let us know what you find.

[Compass1]

I found out that the rear cats are broken on my 2003 Porsche Boxster S. The noise that is produced in and around the exhaust when the car gets hot is very loud. Porsche will not replace the broken cats on warrrenty because no failure report is made when the car is plugged into the diagnotic machine. Does anyone out there have suggestions for repair or replacement? Names of exhaust products and contacts in the US would be appreciated. Thanks, Richard

[nefarious986]

I don't hear a rattle when I drive, but when I'm parked after a hard drive, or even a normal drive sometimes, there's a crackling noise from the exhaust area.

Is that normal ?

Originally Posted by nefarious986

I don't hear a rattle when I drive, but when I'm parked after a hard drive, or even a normal drive sometimes, there's a crackling noise from the exhaust area.

Is that normal ?

Yes, that's the exhaust, mainly the cats, cooling off. Metal expands when hot. Then starts to constrict during the cooling process.

[vipola]

I had a such viration noise on my left cat, it was happening exactly at 1000 rpm (sometime at 2000 rpm).. finally a small solding tak fixed the vibration

get a rubber hammer and hit at different places until you can reproduce the sound

[Cloudsurfer]

Correct me if I'm wrong, but aren't the manufacturers required to certify emissions components for 80k? I had both cats replaced on my last BMW at 70k under warranty.

Patrick

[RandallNeighbour]

If you are positive the cats are bad, then I'd buy some salvaged ones from LA Dismantlers or Oklahoma Foreign.

However, your onboard computer would be telling you if anything was wrong with those cats.

My guess is that you have a small, loose piece that needs a whack or two with a hammer.

I had the same annoying vibration coming from the passenger side cat and got under the car when it was cold and start tapping on various things with the head of a screwdriver and found it was a heat shield (not the thin stuff, but a thick steel one).

So, I got back under there with a hammer and gave it a couple of good whacks and tapped on it again and heard nothing... so I took it out for a spin and that was the problem after all.

You should definitely try this or have an independent mechanic tap around for you if you don't have ramps or floor jacks.

Do let us know what the final solution is on this thread so others can learn year after year when they do thread searches.

[Adam]

Originally Posted by bmwm750

Correct me if I'm wrong, but aren't the manufacturers required to certify emissions components for 80k? I had both cats replaced on my last BMW at 70k under warranty.

Patrick

Exactly, this should be covererd by warranty if the cats are in fact bad.

[dj1]

The cats aren't technically bad if they pass emissions, even though the rattle indicates they are beginning to break down. The noise is annoying for sure, but it's probably not possible to get the manufacturer to warranty them unless they fail the emissions test. Good luck.