at the bottom of the coolant reservoir tank.
thermostat or blown head gasket....
It sounds like the tank has a leak.
Yes- coolant reservoir is designed to accept excess coolant - As coolant heats up it will expand and flow to the coolant recovery tank (reservoir) and as it cools (contracts) it will be sucked back into the radiator
As the engine coolant heats up, the coolant expands, so the coolant needs a reservoir or expansion tank to flow in and out of as needed.
A surge tank is basically a pressurized coolant reservoir. As your engine heats and cools the coolant expands and contracts. Because of this You need a place for extra coolant to go to when it expands and be drawn from when it contracts. Conventionally the recovery tank or reservoir was not pressurized. A tube from the radiator cap allowed coolant to be sucked and drained in to the reservoir. However, on many newer vehicles like yours the reservoir is pressurized and called a surge tank.
A 1966 Grand Prix did not come with a reservoir tank. You can add one though.
coolant overflow/reservoir tank
Near the bottom of the coolant reservoir ( overflow tank)
It cost me $185.00. That includes $85 for new reservoir tank and coolant & $100 labor.
The reservoir is usually considered to be the tank which holds coolant. It feeds the coolant into the radiator when needed, and receives coolant from the radiator as is necessary. This is where you check and maintain the coolant level. Make sure the cap is on quite tight.
If no cap on tank must use reservoir.