I have a 2001 WRX.

The rear wheel arches are showing signs of paint starting to blister where the rear arch meets the rear bumper.

I believe that there is foam between the 2 skins which may be holding moisture.

Are there any bodywork specialists out there that have seen this before and can offer any advice ?

 

It needs to be cut out and a new piece welded in, then smoothed off, repainted and re-sealed at the rear. Not cheap, and needs done sooner, rather than later

 

I was more concerned with what to do about the foam that appears to be absorbing moisture & causing the problem.

Presumably, that needs to be removed and the underside rustproofed rather than foam re-applied ?

 

Do Subaru not have a 10 year anti - corrosion warranty??!!

 

Not sure what the foam is. Is it the rustproofing layer? If so, it would want putting back, or something else putting on. So long as it's SEALED again, it ought not to rust. It does rust because there is a bolt holding the bumper there and even a slight bumper knock tears the lining allowing moisture in...according to a bodyshop near me

Not sure how long, but yes, they do, so long as you've had the bodywork cleaned, checked and any running repairs done, yearly.