Intermittent exhaust growl

[DiamondDave944]

A couple of times over the past few weeks I've noticed an intermittent growling noise from the exhaust.
It is very intermittent and when it happens it is when I'm pulling away from a standstill and only lasts a second or so.
I've had a look and don't see anything obvious and the best way I can describe it is that it sounds like a blown exhaust.

I drive the car to and from work every day and it happens once or twice at most during the round trip.

Anybody had anything like this? or any idea what could be causing it?

Thanks in advance.

DC

 

[911sse]

Having been in the same situation a few years ago, I'd check around the manifolds for any leaks.

 

[DiamondDave944]

Thanks,

I'll have look and let you know what I find.

DC

 

[NickChivers]

Hi - any update on this ?

 

[SteveGo]

My recently aquired Boxster S has similar growl from cold, I haven't had a good look yet but it does sound like it may be a loose heatshield or similar. Gone when system is warm.

 

[BrianJ]

Make sure the lambda sensors haven't unscrewed themselves. There are 4 on a 2003 2.7 - one upstream and one downstream of the cat on each side. I found mine came loose a couple of times in the 6 years I had the car - just tighten with a spanner. You'll know if they are loose - they wobble about in your fingers!

 

[SteveGo]

Backed car onto ramps to investigate exhaust buzz/rattle and found it to be a loose heatshield on the upstream side of the left side cat. Would appear that the shield is attached (by spot welds)to the pipe at manufacture and can't be replaced seperately. Both sides are affected by corrosion but only the left is loose.
Temporarily fixed by twisting the seams with mole grips to tighten shield onto the pipe!
Ultimately the pipes (and cats) need to be replaced to properly effect repairs but this would be hugely expensive!
Any reason why I couldn't remove the shields altogether and lag both the pipes in asbestos bandage? [8|]