Anyone got suggestions on how
they have in the past been able to
seal tiny coolant system leaks?

I have had a small leak at what i thought was
the thermostat housing on my 1995 Magnum V8 Ram,
but after two tries to unsuccessfully fix it "down in the hole"
including using a snake video borescope,
yesterday i tore down the front of the engine
by removing the accessory bracket that holds the
alternator and air conditioning
in order to see every thing more clearly,
and redid all five possible leak sources...
Two temperature sensors,
the heater inlet hose,
the thermostat housing ( this time with Right Stuff and no paper gasket)
and the bypass hose.

Before putting everything back together,
i borrowed a radiator pressure test kit from O'Reillys Auto Parts
and pressurized the empty system and non running engine with air to 16 psi,
and then painted all the joints with soapy water
looking for the bubbles indicating leaks.

The good news was that
none of the stuff i had just redone
showed any leaks this time.
( the prior pesky leak was probably the heater hose nipple)

But the system would not hold
a steady 16 psi like it should have.

16 psi
would decline to
12 psi in
37 minutes.

Much more painting of other joints in the cooling system
finally showed that there was a
tiny leak in the timing chain cover gasket
at the top driver side corner.

Your suggestions for
simple cheap and easy fixes?

Yes,
the engine now has
198,000 miles
and probably needs a replacement for its OE
timing chain and
water pump
anyway.

It still has the unusual NPG coolant
without any water in the mix (all propylene glycol)
but i am thinking of draining it out as
$35 per gallon
makes any leak expensive.