Hi, all. New here, so please forgive.
I did a search of the group to see if any of the previous topics were
relevant, but didn't find one that fit "just right."

I have a 97 Taurus GL sedan with a 3.0 vulcan. My wife drives it as her
daily car. About 30 miles a day. Suddenly, it starts running hot and
spitting fluid from the recovery tank. Found and patched the
pinhole...)

I had replaced the water pump about 10 months ago. (did the work
myself. My time is only worth $18 an hour, not $60...) So I assume that
that isn't the problem.

Clues have me confused.
1) Brownish Rad Fluid, that continues to get brown, even after a
flush...
2) No water showing on oil dipstick.
3) No heat.
4) Fans and circulation _seem_ fine.
5) As mentioned above, new-ish water pump.
6) Rad. fluid (water alone, until I get this figured out...) does not
show signs of oil. No foam, no slick feeling to it.
7) No steam from the tailpipe, unless the outside temp is below
dewpoint, and the engine runs like a top. Plenty of power, and no
stalling/rough idle.

Swapped out the thermostat for a new one, and it only seems to have
helped a little. Still behaving like it wants to overflow at the
recovery tank. (Pressure cap seems to be doing its job...)
Gauge reports that the temp is good. (lower third of the scale), but
it's still building up what I consider to be an abnormal amount of
pressure in the system.

Running with the pressure relief cap off the recovery tank, it makes
this rapid fire gurgle sound when it reaches operating temp. The fluid
level will rise and fall. I've never heard any such noise from any car
before...
(Who's bright idea was it to make the recovery tank the only way access
the radiator fluids without tools?)

I have read here about some type of heater core bypass kit, but
wouldn't know it if it leapt out of the engine compartment and bit
me... From what I can see under the hood, it sure looks like there are
"T" junctions on the heater hoses, but, I'm no expert.
(This raises the question of whether or not I have the flush kit
installed in the right place...)

Wonder if any of you have run into this before, and if you might have
some advice for a self-taught driveway mechanic whose last engine
rebuild was a Olds 350 Rocket, 20 years ago.
I've been buying "Cheap" cars, and keeping them going well past the
"Sell By" date for many years, but this one has me stumped.

Thanx in advance.