Well it leaks.
Volkswagen Q&AAsk Your Question
2003 Volkswagen Golf Question: how to repair water housing and the o-ring?
Answer #1G. T. Service Center (4231 Answers) , Stephenville, TX - (254) 638-3236ProfessorG November 12, 2013, 06:01Master
Try www.alldatadiy.com for information.
Answer #2Greg's Orange Auto (14238 Answers) , Orange, CA - (714) 361-9386globalhelper November 12, 2013, 06:01Master
reseal and repl thermostat & housing