Originally Posted by Denny Graham
Even the original Harrison Deluxe AD heater cores were only
made to take 7psi max. When you get them up to that pressure
and hear them creaking you may have gone to far. Ask any of
the old time radiator repairmen if you doubt me.
I don't know, but the reproduction ones they are selling today
may, like so many other things that are copied from an
original, just may be marginal also. Example, door latches,
headliners, light switches, tail light housings, rubber
parts, etc.

Your Lincoln Towncar heater would have been made to take the
higher pressures that the newer cars carry. But I am surprised
you're running air supply (120-150psi) thur it and that is
hasn't burst one of the tubes.

DG

I was too.
I only tell the story to illustrate there is a range of pressures at which things fail... or not.

Give me ambiguity
or give me something else