My exhaust started blowing and I had the downpipe and middle section replaced. While this is basically OK and the exhaust is no longer blowing, I now detect a new and puzzling noise, difficult to describe, with a ‘metallic crackling or tinkling’ evident only on acceleration, or when needing some power on hills etc. When cruising or under engine braking downhill it disappears.
I took the car back to the garage and the foreman put it up on the ramp and invited me to inspect it with him, confirming all with the new installation seemed OK.
Any idea what might be causing this new and puzzling noise?
Could it be a loose baffle inside the box?
Hmm... this would be inside one of the existing silencer boxes that were not renewed? I don't know, but strange that the noise has started after the work carried out on the exhaust. By the way, this is a 1.6 petrol Driver.
I was puzzled, by the way, to see a bit of double pipework as part of the downpipe/front pipe that has been fitted. Not sure why it's designed like that. Not the same, for example, as the VW Heritage part (https://www.heritagepartscentre.com/uk/191253091aq-exhaust-front-pipe-1-6-petrol.html) specified on their website.
Maybe some progress here. I was intending to replace the very tatty flexible metal tubing from air intake to carb and have now done this (http://www.martinsawers.co.uk/links/InletTube.jpg).
Intriguingly, this seems to have greatly reduced the noise previously referred to, but not 100%.
Incidentally, I also fitted my newly acquired one-piece scuttle (http://www.martinsawers.co.uk/links/Scuttle.jpg) from SWG Motorsport (http://www.swgmotorsport.com/asps/ShowDetails.asp?id=272). Rather pricey, but I'm pleased with it.
Just a thought, grab the engine and see if you can rock it in the bay.
It might be that your front engine mount is failing, allowing the engine to swing back and touch the bulkhead?