CGT cooling woes (help!)

[TEX TERRY, II]

From: qshipaz at juno.com
(snip)
Patient: '86 CGT
Symptoms: Blows its coolant without running to a hard boil. Fluid comes
out=
 the reservoir cap.
Past attempts at correction: Flushed radiator with CLR cleaner after
removi=
ng it from car. Flushed many, many gallons of water thru afterward,
whereup=
on flow looked OK. Replaced cap as well at this time. This cured the
Coupe'=
s desire to ralph until recently. About two weeks of doing OK.
When it started happening again yesterday, we replaced the missing t-stat
w=
ith a new Wahler 80c. Checked the fan switch for operation. (Fan OK)- it
wi=
ll do the burp before the fan even comes on due to temperature. I tested
th=
e reservoir using a tire pump-it's OK.
Note: The heater hose has been bypassed- I was thinking air might be
trappe=
d back there, but when the valve is closed (almost always here in AZ!) no
c=
oolant flows. So I didn't find this pertinent- am I wrong?
I'm a little stumped. Yes, I bled the air bleed bolt at the top of the
meta=
l radiator. Anyone BTDT? I'm thinking radiator's still clogged...
(snip)

Try to get a radiator pressure testor (borrow one from a garage, or take
the car in and have them test it) so that you can test the cooling system
for leaks.  If you have a faulty head gasket, then the engine compression
pressure will be getting in to the cooling system.  This will cause the
overflow condition, even with a new good cap.  When you were using the
bicycle pump, if you have a gauge with a check valve connected, you should
be able to see that the pressure, that you pumped in, was leaking down, if
you have a leak or blown gasket.  If you place a gauge on the cooling
system, then while the engine is running, you should see the irratic
pressure build up, caused from the head gasket leak, which is what the
garage would be doing.

Tex Terry, II
83 5kt Sedan (non-quattro)
Franklin, PA  USA