Rad plastic inlet failure mode

[Dave C.]

I can't resist chiming in with my recent experience.

My wife's 89 100 still has the original radiator... fifteen years old now,
with 150 k miles.  Two weeks ago she drove a 30 mile round trip on the
freeway.  That evening she casually mentions that the air conditioner
suddenly stopped working.  I have no idea why that would happen, so I pop
the hood for a look-see.  First thing I notice is reddish colored stuff
splashed around, but can't seen any obvious source.  Next I notice the
coolant overflow tank is empty ... Uh-Oh!  Poking around a bit more I find
the radiator neck snapped off, but dutifully keeping it's place, so it
looks fine til I touch it and it flaps around on the end of the hose.

So it appears the engine temps rose to the point where the A/C shuts off,
but my wife never noticed anything else...  no idiot light, and naturally
would not have looked at the temp gauge.

At that point I'm worried about engine damage, not knowing how long she
drove around with no coolant.  I had on hand one of the official Audi
plastic radiator neck repair pieces.  So I hacksawed the stub of the neck
to create a smooth end and glued the new stub in with J-B Weld (overkill no
doubt) and let it sit over night.  This repair takes about fifteen minutes,
not counting waiting for the glue to set up.  Next day I pour five quarts
of coolant into the system, which means it still held three.  I take it for
a test drive and all seems normal ... two weeks later and no problems,
coolant level remains steady, so I guess we are lucky the engine wasn't
damaged.  I suppose I should plan on replacing the radiator at a convenient
time.

BTW ... I know the turbo engines run a lot hotter than the non-turbos, and
I'm sure the plastic would deteriorate much more quickly with the higher
temps.  so I don't think the longevity of this radiator would say anything
about what to expect on a turbo engine.
-----------------
Dave C.