American steel makers yesterday refiled their unfair trade complaint against the Japanese despite strong hints from U.S. Trade Representative William E. Brock that it would be rejected by the Reagan administration. Brock is expected to issue his ruling by Monday.

The complaint by eight major steel companies and the American Iron and Steel Institute, originally filed Dec. 15, asked the government to cut imports of Japanese steel by almost one-third over the next four years.

It was withdrawn Jan. 31 to give Brock a chance to negotiate export limits with the Japanese during his recent trip to Tokyo. Instead, Brock came back with an agreement that both countries would closely monitor Japanese steel exports to America. This, however, was unsatisfactory to the U.S. steel industry.

"The refiling action was taken reluctantly in view of the good faith efforts of Ambassador Brock and the Japanese government to resolve the matter," said David M. Roderick, chairman of United States Steel Co. and head of the AISI.

"It is quite clear to us," Roderick continued, "that past injury and future injury are not going to be avoided by well-meaning but vague words. We believe a more definitive understanding--removing all harmful, unfair trade abuses--is vital to the well-being of the domestic industry. The abuses described in the petition are long-standing and need correction."

The complaint charged that an agreement to limit Japanese steel exports to the European Community led to the diversion of Japanese steel here. Furthermore, the complaint charged that Europe and Japan set up a secret cartel to divide much of the world's steel markets between them.

Brock indicated strongly last week that he found little merit in the steel industry complaint. He said, moreover, that Japan had cut its steel exports to the United States by 30 percent last year and that Japanese steel is not the "major difficulty" facing the American steel industry.