how to seal new heater matrix?

[flatyre]

Hi guys I'm replacing the heater matrix on my 1999 1.9d. I picked up a very good second hand one complete with the two o rings which look in good shape. As I don't fancy removing the dashboard ever again, would putting a skim of silicon (just a fine film) around the matrix flange and inlets help create a waterproof seal of be a total waste of time? cheers John.

[Tomcat3]

Get new o rings at least as they will have been compressed for years, they only cost a few pence.

[finny]

a brand new heater matrix is under £20 at euro car parts http://www.eurocarparts.com/ecp/c/Citroe...ter-Matrix