Just installed new Volvo 850 expansion tank and when i turn off my car all the antifeeze goes away?

If all the antifreeze is disappearing after you turn off your Volvo 850, it could indicate a leak in the cooling system, possibly from the new expansion tank or related hoses. Check for any visible signs of coolant leaks around the tank and connections. Additionally, ensure that the cap on the expansion tank is secure and not damaged, as a faulty cap can cause coolant to escape. If the problem persists, consider checking the water pump and radiator for issues.