DEARBORN, MICH., SEPT. 13 -- Negotiators representing the United Auto Workers and Ford Motor Co. intensified their talks tonight in a last-ditch effort to avert a strike against America's second-largest auto maker at 11:59 p.m. Monday.

The talks resumed early this morning and were expected to continue past midnight, and possibly all night. Both union and company officials said they were growing pessimistic that a contract could be agreed upon before the strike deadline.

"Patience is indeed a virtue, but our patience obviously is wearing thin as the clock ticks away," UAW President Owen Bieber said tonight.

A central issue in the talks has been a union demand for job security, a controversial matter during a time when most industry analysts predict a worldwide decline in auto employment over the course of the three-year contract now being negotiated.

Union and Ford bargainers have been talking about little else here in the last two weeks.

"Job security has indeed been the main area that we have been wrestling with, and our differences there are still very serious," Bieber said, adding that if bargainers failed to reach an agreement, "It won't be because of small differences, it'll be because Ford has failed to meet the challenge" of securing jobs.

The UAW chose Ford as a strike target two weeks ago in its negotiations with Ford and General Motors Corp. The GM talks have been held in abeyance until the Ford matter is settled.

At Ford, where hourly employment fell from 191,400 workers in 1978 to 104,000 today, the UAW has offered a radical proposal that would forbid layoffs for any reason, including economic downturns and poor sales. The UAW in effect is asking Ford to retain all 108,000 UAW workers -- including those now on temporary layoff -- who currently are carried on the company's payrolls.

Bieber said that the union's request would pose a problem for Ford only if the company intended to shift more of its manufacturing work to non-UAW plants, both foreign and domestic. Ford now uses non-UAW sources for at least 50 percent of its component manufacturing.

"Ford has known clearly where it has to go for us to be able to reach an agreement by deadline," Bieber said.

However, Ford's chief bargainers indicated that the job security proposal would present a substantial obstacle to a settlement. "There are no off-the-shelf solutions" for the kinds of problems raised by the proposal, said Peter J. Pestillo, Ford's vice president for employe and external affairs. Making a mistake in implementing such a program "could prove costly," he said.