Glue it back on firmly?

The heavy duty insulation attached to the underside of my 1998 Peugeot 406 bonnet has lost its shape and collapsed.

I am not sure if the insulation is just sound-deadening (I am happy to remove it) or if it protects the bonnet from the heat of the engine.

I would put money on it being just for sound insulation. But only by analogy with Pug 205s: I think only the 1.6 and 1.9 petrol engines had underbonnet insulation. The uninsulated bonnets get pretty warm, but the sun can do that too.

If the stuff is flopping onto the engine, probably safer to remove it. Though many years ago I used to keep a heavy blanket under the bonnet of my Morris 1100 during the Canadian winter ....

Edited by Andrew-T on 04/08/2013 at 19:17

These insulation pads are primarily for sound insulation. You can safely remove it if you feel you must, but may have to put up with increased cabin noise. There will defo be increased external noise.

Is the rubbing causing a problem? Why not just leave it?

You'd never glue it into place without getting hold of some serious temperature resistant adhesive. Nothing on the shelves of any of the DIY stores would do the job.