Q: white smoke after head gasket repair

When ever an engine blows a head gasket and leaks coolant into one or more cylinders and pushes the coolant into the exhaust flooding the catalyst and muffler with coolant. After the repairs to the engine are made to fix the leaking head gaskets the engine can then be started. Once started the exhaust heat will now start to burn off the coolant and water that was pushed into the exhaust system. When this fluid is heated it will come out the exhaust as white smoke or steam. It may take a few days to a week to burn off all this fluid out of the exhaust. One of the quickest ways to burn off all the coolant quicker is to hold the throttle at about 2000 rpms when in park for about 10 to 15 minutes. This will get the exhaust to its hottest level and burn off excessive fluids out of the exhaust. Just a note that the coolant that got into the exhaust system may of contaminated the O2 sensors and the substrate of the catalyst. If you start having check engine codes for the O2 sensors or catalyst efficiency then you may need to test and replace the catalyst and O2 sensors to repair the codes.