The four-day strike by 3,400 workers at a General Motors metal fabricating plant in Flint, Michigan has already begun to slow down production at other plants owned by the giant auto maker. On Monday morning a plant in Orion Township, Michigan shut down production, due to a lack of parts, idling 2,800 workers.

Analysts say the stoppage could quickly end the supply of hoods, fenders, doors, engine cradles and other stamped parts for GM’s highly profitable full-size pickup trucks and sport utility vehicles. Several large and mid-size cars, including Cadillac models, would also be affected. As many as 18 plants in the US, Canada and Mexico could be closed in less than two weeks, costing the company $300 million a week in profits.

Representatives from United Auto Workers Local 659 and GM continued to talk throughout the weekend and Monday, but no resolution was reached. Workers are protesting unsafe conditions, like exposure to toxic chemicals and damaging noise levels from the huge stamping presses, as well as the lack of hiring, outsourcing and scores of unresolved grievances. The UAW also accused GM of reneging on its pledge to invest $300 million to expand the plant.

More than 5,800 workers at GM’s nearby Delphi East facility, members of UAW Local 651, have also threatened to strike, beginning Thursday. They produce spark plugs, fuel system components and instrument clusters for most of the vehicles GM builds in North America.

Workers are angered over GM’s continuous destruction of jobs in Flint, the birthplace of both GM and the UAW. In the late 1970s nearly 90,000 workers were employed by GM in the area. Now the figure is fewer than 30,000.