One problem related to blown head gasket has been reported for the 2006 Toyota Avalon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Toyota Avalon based on all problems reported for the 2006 Avalon.
Head gasket leaks both sides. Under repair. Poor design or manufacturing. Should not have occurred at this mileage level. My repair service indicated that this has happened on several Toyota products. Concern for accident potential should head gasket blow at high speed in heavy traffic where conditions do not allow for a safe exit from travel lanes to shoulder. Note: vehicle registered under my wife maria's name.