I'm back to an old problem. The sable is spurting coolant out the cap. The only time it does this is when you come to a stop after running a while. The gauge never gets over halfway, but you can hear the coolant chug everytime I shut it off. I have replaced all the usual suspects, including the cap and thermostat, hoses, water pump,rotted the radiator twice and back flushed the heater core. The engine runs great and I get no smoke as you would if the heads were burnt. It is possible the heads are warped and this is causing the problem? The only thing I have done since last time this happened was to replace thecataylic convertors to get it inspected.Any help will be appreciated.

Have you ever replaced the rad. cap? What does the underside of the cap look like? And how much fluid is in the reserve tank when it's cold? Hot?

warped head

I have replaced the expansion tank and also the rad cap. When it is cold there is just enough coolant to cover where the hose is connected. As long as it as at this level it never spews. It only seems to spew when I top it off to the lines on the expansion tank.