On my '85, the rear heater core was definitely leaking.  I ordered a new
one from Ken, at vanagain, and requested two of the O rings as only the
O ring was leaking in my '84.  I figured that replacing the ring that
wasn't yet leaking in the '85 was preventive maintenance.

The O rings I received, which are working fine, are not traditional O
rings but look more like ends cut from a tube .... in other words, they
have flat edges.

Mike

> Okay, I finally got around to pulling out the heater box from under my
> rear seat. I pulled the old (leaky) heater core out and noted that
> there is a (previously unknown to me) switch to control the coolant
> flow through the heat exchanger. I unbolted this switch in preparation
> to put it on the new replacement heat exchanger and noted that the
> o-ring (?) was pretty darn stiff and was no longer o-shaped in
> profile...
>
> Not a big surprise for a 13 year old vehicle. Since my new heat
> exchanger didn't come with that o-ring, (and no mention in the bentley
> of anything special here) I put it to the list if there is anything I
> should be aware of towards getting a replacement one? Otherwise, I'll
> just visit my local flaps and get one appropriately sized.
>