It will be cold work, but as long as you don't let your vehicle sit with just the water and flushing solution to freeze (like a few hours) there is no hazard of damaging your cooling system. Safe conditions in below zero weather are as follows:
Vehicle running (it will produce enough heat to prevent freezing no-matter how little anti-freeze is in the system while running)
Coolant system drained - if there is no water in the system to freeze - no hazard.
Coolant system filled with the appropriate amount of anti-freeze solution in the coolant.
Make sure you take adequate protection against the cold for yourself too!
Answers & Comments
It will be cold work, but as long as you don't let your vehicle sit with just the water and flushing solution to freeze (like a few hours) there is no hazard of damaging your cooling system. Safe conditions in below zero weather are as follows:
Vehicle running (it will produce enough heat to prevent freezing no-matter how little anti-freeze is in the system while running)
Coolant system drained - if there is no water in the system to freeze - no hazard.
Coolant system filled with the appropriate amount of anti-freeze solution in the coolant.
Make sure you take adequate protection against the cold for yourself too!