Exhaust noise on startup

[ravi911]

Hi all

My 05MY 997 has started making a very loud noise after startup which sounds like a blown exhaust or an old Harley or indeed a Max Power Saxo! This lasts for the first few minutes of driving and then disappears.

Doesn't appear to affect the driving in terms of power delivery but the noise is awful and not what you want when driving in a built up area.

My thoughts were that it is to do with the startup phase where I believe there is a valve in the exhaust that helps to reduce emissions until the catalysts warms up.

Any ideas?

Ravi

 

[Geoff_Fields]

Mine has made a strange clatter noise from the exhaust when cold from new, which always dissapears after a couple of minutes.

 

[stomper]

Mine does the same, so much so I thought it was going to fail the MOT but it didn't and I even checked with the service manager at the OPC and he said it sounded fine to him. Mine settles down almost immediately but that first 20 seconds sounds brilliant.

 

[garyw]

Mine makes a wonderful noise on startup for about 30seconds and then goes into a muted rumble..[] []
I assume its the fuel ratio mixture for startup in cold conditions....

garyw

 

[ravi911]

Doesn't sound like any of these I'm afraid. Real blood and thunder stuff!

Also this is new. I've had the car for over nine months and not heard anything like this before.

 

[Keggers]

I'm no expert and simply passing on what i've read, but I have read on forums before that you can get a leak at the connection between the manifold and the engine due to a loose manifold bolt or two, and that it sounds really loud on startup as a result when the manifold is cold, but when the manifold heats up it expands and seals the leak, making the excess noise disappear. Probably not what you have, but may be worth considering.

 

[ravi911]

Hi Keggers

Turns out that it was something like your suggestion!

Yesterday as I was driving to see a friend in Newport Pagnell (actually the guy who runs Export 56 - buying/selling/restoring old Porsches) I noticed some strange handling. When I arrived, I found a flat right rear, with the sidewall sadly damaged beyond repair as I had been driving []

Luckily, Mick knew a tyre place down the road and a quick phone call secured a couple of new Conti Sportcontacts to be delivered today morning. So we put some air in the tyre and drove the car (slowly) to Formula 1 tyres to leave it overnight for the fitting in the morning.

While there, I mentioned the noise to a friendly chap by the name of Steve who said that he would put the car up on the ramp and have a look.

A few hours later, I got a call from Steve to say that he had found that some bolts had sheared in the system and that he had managed to drill them out, re-thread, put new bolts in and seal the joint so all was now ok []

When I went to pick the car up this morning, no Steve (day off) but a bill for only the amount agreed for the tyres []

Now that's what I call above and beyond the call of duty!

I need new rears on my 993 and guess who's getting the business!!!

Many thanks to the guys at Formula 1 in Newport Pagnell