Congrats on the successful fix, I did the same expansion tank fix about 3 month ago or so. Only difference in my case was, I had to change part number 12 shown in ur diagram because when the expansion tank thermostat disintegrated;half of it stayed in there. During the process of removing it, the 12 part started to fall apart literally it was so brittle... So the one couple hr job became 4 day because I had to order the part and wait til I get it. At the end, it felt good driving a car that has one less thing that leaks lol....

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2001 BMW X5 3.0 Sold
2008 VW jetta S
2006 Lexus Rx400h