Q: What would make antifreeze come out of a tail pipe after a water pump was replaced?

Hi, thanks for writing in. The replacement of the water pump will not cause water to come out of the tail pipe. The overheating before the water pump was replaced most likely caused the head gasket to get blown from a warped head gasket. Have the cooling system pressure tested to see which cylinder is leaking coolant into the exhaust. The engine may need to have the heads removed and checked for warpage and cracks then gaskets replace after heads are checked and repaired or replaced as needed by the machine shop. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.