rattle from 2004 996 c4s exhaust when cold HELP PLEASE

Hi Guys I am new to this site, and this is my first 911. I bought the car about 4 weeks ago, and I have noticed that when the engine is cold there is a rattle from the back passenger side of the car... sounds like there is somthing loose vibrating and making a noise until you get over around 4000rpm or in 4th-5th gear doing about 35-45MPH the car has the switchable exhaust (I think is standard??) can you please let me know if this is a serious problem and how I can fix it. Rough estimates of cost to fix would also be great if possible your replies would be greatlly appriciated Dave

It could just be the inside of one of your exhausts has had a weld failure on the metal parts that direct the flow of gases (they're not strictly baffles but similar), can you get someone to rev it slightly whilst you stick your ear to either side of the car when stationary to listen out for it? When the exhaust system becomes hot and expands it would probably stop the rattling. Also on the switchable sports exhaust there are 2 vacuum operated valves that open and close in a certain rev range to reduce noise in urban areas and within a certain speed range. You could also check these for operation or noise. There is a relay you can remove that will cancel out the valves and bypass them, this leaves the exhaust system in LOUD mode and may stop the noise you're talking of.

Thanks for that Marcus doesnt stop when in loud mode but still seems in the exhaust area, I think it is exhaust related, but cannot 100% convince myself regards Mike

Mike - it could be an external rattle from one of the vacuum actuators that operates the valve from loud mode to quiet mode. This photo is a genuine PSE muffler (my own in fact) and will give you an idea what can rattle on the outside of the silencer i.e. the link rod to the valve. Where the rod screws into the balljoint, there is a lock nut. If you can get at it, slacken off the locknut and a small adjustment of this rod may just tighten up any loose play and stop a rattle. Just a thought.... Enjoy your 4S - I think they're one of the nicest looking variant of the 996 breed, and with PSE they have the music to compliment their looks. :thumb:

Thankyou for your kind words I think the 4s is the best as well thats why I bought it, I will probably have to live with it for now,many thanks Mike

Thaks for the advice MQ and Nick I will have a look with my mechanic Seems like you have the same problem here mike let me know if you manage to find the fault and I will do the same. this post got a little confusing with me asking the question and mike replying with thanks lol.... I will keep you updated,and Oh I also think the C4S is one of the better looking 996's available. Are the Turbo style wide rear arches standard on the C4S? Dave

I dont think I helped matters by replying to Mike :roll: The C4S has the wide body as you would find on the Turbo, with the exception of the intercooler inlets on the rear wings and also the rear spoiler. It also shares many other important goodies with the Turbo. On the whole, a fine looking 996. :thumb: