Sealing tail lights - water leak

Tony Hoffman auditony at
Wed Oct 26 10:36:37 PDT 2011

I use 3m 08611 butyl, same stuff that Audi used. If the taillight itself is
cracked and leaking inside, the bottom of it will have to fill up at least
1/4 of the way first. IOW, look at the taillight assy from the outside and
see if it is 1/4 full with water in the bottom. If not, your problem is
around the butyl seal. If it has water inside, the taillight itself is
probably suspect. Time to upgrade to V8 taillights!! Yipee, I love excuses
to upgrade ;-)


On Wed, Oct 26, 2011 at 10:43 AM, Dave C <dconner at> wrote:

> Water is leaking into the trunk and I think it's from the seal between the
> tail lights in the trunk lid.  This is a 1987 Audi 5000.  I've re-sealed it
> twice already using 3-M strip caulk 08578 but the leak seems worse than
> ever.
> I figure either this caulk is the wrong thing to use, or else there is a
> crack in the tail light which I didn't notice.
> I'm tempted to try re-sealing again with the Audi specific sealing
> material.  It is p/n AKD-497-010-04-R10 (not sure about the last three
> characters in that p/n).  It costs about $60 for a 10 meter roll.
> Does anyone know whether there is a significant difference between the 3M
> and Audi sealing materials?

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