[TR] Overheating with unique solution

[Peter Arakelian]

As those of you who travelled with me to and from Triumphest and some who were
there know, I had an issue with overheating.  The solution was unique, but to
appreciate it let me give you some background.
My car, 1971 TR6, has never overheated.  I have had it to Lake Havasu,
Laughlin, Barstow, Palmdale, other places where it was well over 100 degrees.
In stop and go it may go up some, but as soon as we move temp comes right
down.  Because of this, I did not check the overflow bottle as much as I
should - may be every few months.  For the last year or two, every time I
checked it, it was empty,  The radiator was full, but the bottle was empty.  I
would half fill and go on.
In the weeks prior to Triumphest, the water pump bearing started making some
noise, so I replaced it.  At the same time I replaced the top hose, it was a
little swollen, replaced the thermostat, which I checked and it did open at
temperature, and checked the radiator cap.  The seal at the base of the cap,
where it actually closes off the radiator core, had some pieces broken off the
edge - it looked like a mouse had been chewing on it.  I replaced it.  I
filled the system and the water bottle and drove off.  After the next several
trips, the bottle was always empty.  At first I figured it was the system
filling, but after a few times I realized I was losing water somehow.  No
leaks. No overheating.
I decided to make the trip anyway.  We went from southern CA via Barstow to
overnight in Laughlin.  No problems.  I checked they water in HOT Barstow,
none in the bottle, half filled it.  When we got to Laughlin, about 4PM, I
left the group to run an errand.  When I stopped water was boiling out of the
overflow bottle.  When I restarted to go back to the hotel, the temperature
came right down.  When I got gas I put more water in the bottle, and the next
day we went to Flagstaff.  No problems until the return trip stop in Barstow.
It was boiling out the bottle again, but no overheating on the gauge.
When we got back I took it to a radiator shop we use.  He flushed the system
and checked the radiator flow.  All was excellent.  So I was thinking it must
be the head gasket, even though I was not blowing white smoke.  Then I spoke
with our resident mechanic.  He told me to check the radiator cap.  I told him
I had just replaced it.
Now here it comes:  He explained that the radiator cap is a two direction
valve.  One opens at the rated pressure, the other is on the underside,
radiator core side, of that to let the water back in from the bottle.  He said
check under that.  Sure enough I checked and there were some pieces of hard
rubber - like had broken off the main seal.  Remember my chewed up seal on the
old cap?  Cleaned them out, washed-out my overflow bottle, pulled the overflow
tube off the base of the bottle, and so far no more water loss!  Figure water
was just blowing out the partially opened secondary valve causing all my
problems.

Peter