Radiator, drain cock and guide pin

Identify the type of plastic. See

Select the correct welding filler and set the temperature of the welding gun so that it agrees with the type of plastic. See

Tack the parts in place.

Weld the parts in place with welding filler.

Allow the weld to cool.

Grind the weld if required.

Note
The plastic stamp on a radiator can look as follows:
PA - T 20; where the figure 20 states the percentage of filling material. Only radiators with max. 30% filling material can be welded. A radiator with the marking PA - T 40, for example, cannot be welded.