Method of manufacturing a link rod of a wiper for a motor vehicle

A method of manufacturing a link rod of a wiper of a motor vehicle, comprising the steps of:

• crushing each of opposite end portions of a tubular blank over a predetermined length by stamping;
• punching the opposite end portions of the tubular blank such that a rod body having a pair of flat sections provided at its opposite ends, respectively and a cylindrical section provided between the flat sections;
• punching a first hole having a large diameter and a second hole having a small diameter at outer and inner portions of each of the flat sections, respectively as viewed in a longitudinal direction of the rod body;
• wherein a gap opens into an axially intermediate portion of a peripheral surface of the second hole such that interior of the cylindrical section is communicated with a mouth of the second hole through the gap;
• washing the rod body with cleaning fluid;
• discharging from the mouth of the second hole, the cleaning fluid which has penetrated into the cylindrical section;
• coating the rod body;
• and
• molding a pair of resinous coupling joints integrally with the flat sections, respectively;
• wherein each of the coupling joints includes a joint portion disposed at the first hole and seals the second hole and the gap.