[Non Corsa] Brand new exhaust system failure. Stoopid noise

[AJ]

I got a new exhaust system made and fitted last week - If I let engine run about 3-4k rpm and come off the accelerator, the exhaust sounds like there is a bag of bolts rattling around inside it but stops as soon as i press the clutch down. Any ideas what it might be?
Thought it would be old bits of stock exhaust flaking off but would have thought the place that built it would have removed all that when they welded the new one in place.

[CorsaEdi]

Is it rattling against something on the car?

[Taurus]

It may just need re-aligning. Sometimes they shift a bit when they first get hot. Did they use new rubbers on it? Check they are all in place.

[Vegas]

By system, you mean backbox.

I'd say take a look under where they've worked on it, see if touching anything. Hopefully the car hasn't **** itself

[AJ]

WHen engine is is revving, usually, just before needing to change gear, my exhaust makes a rattle noise as if a thin bit of metal is tapping on it.



At first I thought it was the heat shield above the backbox as this was rusted beyond repair - literally just snapped off, so I removed it but it made no difference.



It's almost like there is a load of thin bits of metal inside the backbox.



A few weeks ago, I had the backbox cut off and replaced with a custom made stainless steel backbox and exhaust tip - this is when I noticed it happening.



Dont want to go back to the place that built it just yet and ask them to check it as I have an idea they will just examine the appearance and say that there is nothing wrong with it and would need to cut the thing in half to see if anything is trapped inside, which there may well not be.



Is there anything I can try before hand?


Getting quite tempted to just stick a hoover pipe up the exhaust and hit the accelerator hard whilst in neutral.



Oh, another interesting thing is, when the rattle starts, simple holding the clutch down will stop the rattle completely....until I lift up off the clutch again.

If I lift the clutch up without engaging a gear, it dont rattle.



Rattle only happens when I'm in gear and the engine is turning the wheels

[Dave]

To be honest the whole clutch thing would make me think a bearing on the input shaft of the box is gone... Without seeing it or hearing it its quite hard to say though.

[nibnob21]

Dipping the clutch may be stopping the noise because by easing the revs off, the engine isn't vibrating as much and therefore the exhaust will stop reverberating.

The baffles in my cat have come loose and they rattle at certain rev ranges or occasionally when going round corners. It may just be something simple like that.

[AJ]

You can hear the noise near the start of the video whilst I'm on the straight
Then again as I enter the first roundabout
And lastly when I approach the 2nd roundabout

[Rocksta]

Video doesn't work

[nibnob21]

Works for me. Doesn't sound like the cat like on mine, but it also doesn't sound like a dodgy gearbox to me.

[Vegas]

You sure it's not one of the other heat shields?

[AJ]

Only other heat shield I can think of would be under the cat but don't have jack to get under to check