Passat B5 heater water tank leaks. What should I do if there is still that smell in the car after replacing the heater water tank?

This is because the repairman stuck engine oil or other oil on the heating box when replacing it. When the temperature of the water tank rises, the oil will evaporate, resulting in visible and audible phenomena. Just wipe the oil off the heating box.

Use argon arc welding to fill the leak, and never use electric welding. The car body is thin, and welding is easy to cause more damage. If the leakage area is large, it is recommended to replace the whole surface.