Ron,

Take care, you may have a real problem and continuing to fault diagnose it
without determining the cause can create more expensive problems!. I've been
there and hope to be on the recovery track many thousands later.

Answer some important diagnostic questions first, before continuing to drive.

First of all the flashing red light on your temperature guage is not, repeat
not an "overtemp warning light"! It is there to indicate a low level of
coolant in the expansion tank. That's the tank inside the engine compartment
and you can see the sensor wires leading to it. So if that expansion tank is
empty, then that's why you're getting the light.

So why's it empty or low of level? That's the important problem and
determining the answer is critical. One possibility is that it simply low on
fluid for all of the possible logical reasons. Straightforward fix.

The other ( worst case) is that you have leaking heads that are pressurizing
your coolant system and driving the level of coolant down through hose
expansion brought about from excessive pressure. This is an endemic water
boxer problem. To test for it: when the water level is down (light flashing)
loosen the cap of the expansion tank ( you'll have to go in through the top
of the engine compartment and remove the overflow tube from the cap in order
to turn it). WARNING: don't screw it off, just loosen it. If air escapes and
the level of fluid in the tank returns to normal , or overflows, then you
have the classic leaking head problem and continuing to run the car will
begin to "blow-things-out" and eventually cause secondary overheating
problems.

Right me for more info. I've become a reluctant expert on this problem.

Tom Ryan