Recently my 2008 S hatch exhaust reverberates only when car is fully warmed up. It only happens at 2000 to 3000 RPM,it really sounds terrible and only goes away when I shift to get it out of that RPM range. It makes the noise on acceleration and deceleration,also the noise emminates from the engine bay. I have about 57k on her and this is a new issue.

 

From the engine bay? If so, you can rev the engine at a standstill and see where the noise is coming from.
Because right now we have nothing to go off to help you with such.

- Erik

 

Yes the noise is noticable from under the hood,it definately is more noticable under driving loads especially going up a hill and when you let off the accelerator it really cackles,but it only makes these noises when the engine is really warmed up and especially the warmer the outside temperature is. Also I have inspected the exhaust system and do not see any leaks from any connections including the turbo. I just wonder if a baffle in the exhaust system is to blame,any ideas are greatly appreciated.

 

I can't do much over the internet, but have you been able to trace the physical location?
There's no exhaust 'baffling' in the front part of the car; the exhaust has an OEM resonator put that's behind the catalyst.
Keep digging and spot checking; must sure the flex pipe on the exhaust isn't cracked.

- Erik

 

Hopefully this weekend I will get a chance to dig into it further, I will let you know what I find. Thanks

 

I finally got to check it out tonight,I had the car running with the hood open and put a broom handle on the accelerator and set the throttle at about 2500 RPM where it was making the noise. It sounded like the heat shielding over the turbo was making the noise so I used a hammer handle to push on the shielding to stop the noise but it stayed exactly the same. The noise is definately in the engine bay and is really noticable on the top side, it also seems to be possibly coming from the valvetrain,also I checked for any leaks in the exhaust around the engine but it is OK. I am wondering if it is a sign the turbo or the valvetrain is about to break. I look forward to any ideas you may have. Thanks

 

So, did you locate the general area of the source?
If there's metallic rattling near the passenger bulge of the valve cover, that's the timing chain.

- Erik

 

If it's making the noise primarily under load, I'm guessing you've got a turbo issue (you also state you seem to think it's coming from the turbo).

Here's a relatively easy inspection you can do.

With the engine off (and cool!) pop the air hose off the turbo inlet and check for play in the turbine shaft. (A little oil in there is nothing to panic about). If it wiggles around, you've got a problem.

 

I checked it some more and it appears the sound is coming from the exhaust down below the turbo where the catalytic converter is. I tried to put pressure on the heat shield but I did not hear any difference. Also I did check the turbo inlet and there was a tiny bit of oil in the inlet but the shaft is not loose.I also checked for noise from the timing chain and the noise is not coming from there. It has been really hot here in Omaha so it is really easy to get the noise to happen. I think this week I will take the converter off to check it out.

 

Small amounts of oil in the turbo inlet is normal and nothing to worry about. If there is no play in the shaft, then the turbo is probably fine. Could be a hole somewhere around the post-cat exhaust line. Even tiny holes in the exhaust will affect engine noise.

Let us know what you find.

 

Check the v-band clamps and the flex-pipe on the exhaust system for cracks / misalignment.
You're very close in locating the issue.

- Erik

 

I finally got a chance to work on it some more and after removing the catalytic converter I found that the core inside it is all cracked and broken. I broke all the guts out of the converter and reinstalled it, the exhaust is now a bit louder but that noise is now gone. I am now debating if I will spend the money to replace it or just run it like it is, especially because we do not have any vehicle inspections here in Nebraska. Also so far I am not getting any check engine lights either. Thanks for all the ideas and support.

 

If it was a catalyst failure, the dealer should have to replace it (regardless of warranty) because emissions are federal mandated by the government.
An example, VW is still responsible for failing catalysts on their vehicles now up to (if remembering correctly) 120,000 miles.

- Erik

 

Thanks for the info I will check with the dealer this week to find out.