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Can someone remind me of the correct process? I know that if you drain at the radiator plug and then refill, it may need a few steps to get the fluid back to normal level after running the car and then topping off again and again. Maybe I can fill both tanks to max, start the car and it will suck that excess max inward? I just recall last time I filled, the temp was getting high but I believe the radiator was still cold. Just don't want to fry the engine & make sure I am doing it right. Thanks.
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I've just done this once, but it does take several heat and cool cycles to get all the air out.

Jack the hind end of the car up and open the vent at the top of the radiator. Fill from the pressure tank until coolant dribbles from the petcock, assuming you have a Fluidyne radiator. Shut petcock, Fill everything to capacity and warm the car just enough so the thermostat opens. Let cool. Repeat.
Thanks Dave. It seems I did it correct last time, it just takes a few steps I guess. If you fill the overtank to the top as well, then wouldn't it suck some of that extra fluid in as well? I guess this isn't a full flush then, since the thermostat is holding some back if I am just emptying from the lower radiator petcock.
Here's the description from 'Pantera Place' - it's the last half of the page that talks about Replacing Coolant Hoses - the job wouldn't be complete unless we refill eh? ...

"I used three gallons of Prestone mixed 50/50 with distilled water and had about one gallon of 50/50 mix left over. To fill the system I open the radiator vent valve and started filling the system until coolant started flowing at the vent. I then closed the vent and continue to fill the system. After the engine has been test run for leaks, I let it cool down and open the vent valve to release any air trapped in the system and added more coolant. This process was repeated a few time to release all of the air in the system. I do not find it necessary to jack up the back of the car to fill the system as the Pantera service manual describes, but it is best to follow what the manual requires.

I follow up on venting air in the system after every outing with the car for a few weeks. It works best to check the expansion tank before the car is started and cold. NEVER remove the pressure cap when the engine is HOT. You could burn yourself with the super hot coolant but you will also allow air to get in the system. When you get to the point that the expansion tank is full to the very top you should be set. After you get to this point add a small amount of coolant to the overflow tank so that as the engine cools down after each outing there will be some extra coolant in the overflow tank to make sure that the system will always keep the expansion tank full and not suck air in from the overflow tank. My overflow tank says about 1/4 full when cold. If you add more coolant than that it will dump it out of the overflow tank vent when the engine coolant expands when the engine is at operating temp. Antifreeze is poison so you do not want it getting dumped out were animals will drink it. Apparently it has a sweet taste and they will readily drink it. I'm calling the tank with the pressure cap the expansion tank and the tank in front of it the overflow tank."
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