Expansion tank for a motor-vehicle cooling system

An expansion tank for a motor-vehicle cooling system, the expansion tank having an inlet port and an outlet port, and comprising:

• a plastic shell comprising:
• a) a container to contain a cooling liquid;
• b) at least two protruding collars at said inlet port and respectively said outlet port;
• at least one of said collars defining a seat extending along an axis;
• at least one tubular insert engaging said seat and coaxial to the at least one of said collars;
• retaining means, axially retaining said tubular insert in said seat;
• wherein said retaining means comprise elastically deformable teeth snap-coupling said tubular insert and said shell to each other.