Metal On Metal Noise When Engine Up To Temperature /Hot

[Erudite]

When driving I'm hearing a metal on metal noise, like a piece of sheet metal scraping against another coming from the engine bay. It will occur at certain rev ranges, when the engine is causing it to vibrate. It will also occur if the car goes over a bump.

It's not the cat heat shield as it was making the noise when I was running the car with a decat pipe.

The problem is it only occurs when the metal gets hot and expands during driving. As soon as I stop there's a 10 second window to try to track down the noise before the metal cools, shrinks and stops making the noise/scraping against whatever it's scraping against.

I've looked at the heat shields that are easily visible when looking down into the engine bay and they all look to be secure.

Are there any other heat shields or anything else that is more out of sight that could be causing the noise?

[Stuey2uk]

Disk splash guard ?

[Joesson]

Probably not disk guards if " As soon as I stop there's  a 10 second window.
So perhaps we should ask @Erudite if the noise is there when stationary with the engine running and blipping the throttle?

[Erudite]

Probably not disk guards if " As soon as I stop there's  a 10 second window.
So perhaps we should ask @Erudite if the noise is there when stationary with the engine running and blipping the throttle?

If I run the car and get it up to temperature, it will make the noise when blipping the throttle after pulling over. However, it's only for a very short period (maximum 30 seconds I would say), after this it stops making the noise. In my opinion it's stopping making the noise as soon as something in the engine bay starts cooling off again.

It does seem like a very short time window for it to cool off but the noise only starts after having run the car for ten minutes or so and getting it up to temperature. When the engine is cold/warming up or very shortly after pulling over it will stop making the noise. It only makes the noise when you're on  or coming off the accelerator (between 2 and 3k revs), going over bumps or shutting the door immediately after stopping the car.

When going over a bump it sounds like the squeak of metal on metal and when it occurs during revs it sounds like sheet metal reverberating. I will try to get a recording of it when stationary. I actually tried recording in the engine bay itself when driving but the noise levels made it indistinguishable.

Edit:

Engine bay video here:

[scm2004red]

The only thing likely to cause a noise is something touching one of the moving parts, pulleys/belts. If it happens when accelerating and decelerating, it's just possible a failed engine mount is allowing the engine to move.

[Dev]

That sounds kind of familiar. That VW bug like sound and breathing/ fluttering  is usually the beginning of the exhaust manifold gasket leak or flex pipe leakage. Check both.

[Erudite]

The vw bug sound has been occurring since the original cat was fitted back on in place of the decat pipe that was on it before. Would this potentially point to a leak somewhere along the cat?

I'll have a look at the engine mounts to see if they may be the culprit, thanks for the suggestion.

I'll check the manifold gasket and flex pipe.

My only other thought on the metallic rattle, with the noise being so susceptible to heat is whether it could be a loose baffle in the exhaust? I have one of these Malian TTE exhausts fitted and I'm wondering if it could be rattling against the inside of the back box when it expands.