I finally did my repair the right way - removed the radiator. (3 bolts on
the bottom, have to move the Hyd pump) For those of us that can't
immediately spring for a new all brass Modine, here is what seems to have
1/4 in threaded barb brass fitting - $1.37 (flared end cut down to
Loctite 'Stick n Seal' all purpose adhesive - $2.44
Super Glue - $.97 (2 tubes, <1 used)
baking soda - $.55
patience - multiple offerings to the Audi Gods...
Drill out the hole where the vent line was. Clean thouroughly with spray
carb cleaner to remove grease/oil/anti-freeze residue. Smear sealer around
the inside (access from the large upper radiator hole). Thread in barb.
Drop several drops of super glue around bard on outside. Sift baking soda
on super glue. Alternate baking soda and super glue around barb to fill in
and gusset barb in place. Sealer sets in 5 minutes, reaches max strength in
24 hours. Don't forget to blow through the barb to make sure you didn't seal
What didn't work:
Various epoxies - wouldn't stick
J-B Weld - shrank and split.
Permatex blue (wouldn't hold the pressure)
Super glue/baking soda by itself
Without accessing the back side of this barb, I just couldn't get it to seal
up. It wouldn't leak much, but it was annoying and I can't afford a new
radiator for 4-5 months. Too many other Audi parts to buy first. As a temp
repair, to get home, etc - the baking soda/super glue works great. I have
added a film canister of baking soda/tube of super glue to my Audi emergency
repair kit in the trunk.
Thanks to all for the suggestions and encouragement.
87 5KCSTQ - on the road again...