Just discovered a strange paint bubble on the rear end of my X350, picture attached. It's very small but definitely three-dimensional, i.e. the area in question is slightly bulbous, asymmetrical, and maybe 15 mm long. Has anyone else seen this sort of thing? I'm really surprised and disappointed since someday that area is going to pop and I'll have to touch it up. (There have been times since December, when I bought the car--a 2004 XJ8--when I've wondered if it the body has been re-sprayed at some point - just little anomalies here and there.)

 

I'm not sure if that panel is aluminium or plastic at that location, but I'm very surprised you have not suffered any "Creeping Lurgy" up to now, as these cars are notorious for a corrosion syndrome only found with aluminium vehicles, (aeroplanes too). Normally this bubbling will start in a crevice where salty water sits and atmospheric oxygen is excluded, but it can also occur on a plain surface where the paint has a very small defect allowing water into the defect.

If the panel is aluminium, you'll need to scrape off the bubbling paint and then you'll find a white powder underneath. This has to be scraped out until you're left with bare shiny aluminium. You can then repaint. I now do my own repairs and once I'm down to bare aluminium, I paint on zinc-rich primer followed by normal primer, then stopper to build the surface, then flat it off and repaint with an aerosol top coat. then clearcoat. Of course you could also get a professional shop to paint the whole panel at much greater cost. This shop must be up-to-speed on aluminium panel repainting or there is a danger of the problem returning.

http://aluminium.matter.org.uk/conte...eid=2144416691

 

No, that panel is plastic.
Sounds like a flaw with the paint/prep.

 

Just to confirm this is a plastic panel.

 

If it's plastic, then a repair should be even easier. I have to say I've not seen this defect on plastic panels (yet !!). Maybe a repair has been done by a previous owner, but not properly. Like all used cars you never really know how the car has been treated before you take it over.