U.S. District Court Judge Louis F. Oberdorfer increased the pressure to end the Metro transit strike yesterday by ordering these strikers to show shy they should not be held in contempt of court and by ordering Metro and the union to settle the key pay issue by Aug. 6.

Oberdorfer also ordered the union to tell its members that their strike is illegal but they have recourse through grievance procedures and the courts to resolve disputes - something he clearly felt all of the members did not understand.

There were conflicting signals about whether bus service would be restored today and no indication at all about subway service tomorrow. William Scoggin, the Arlington driver who had served as spokesman for a strikers' committee, announced late last night that Arlington garage drivers would return today. Metro had no similar word from its seven other garages.

Scoggin's announcement underlined the confusing nature of the strike, because he was replaced last night as spokesman for the strikers' group by Eugene Ray of the Four Mile Run garage. Ray said the committee, which met at a home in Southeast Washington, had decided "not to go back to work as of yet."

He said the informal committee was trying to set up meetings at noon today at each division headquarters to report to the strikers about the court hearing and to solicit opinions on what to do next.

Ray said the group would hold a mass meeting of strikers at 6 p.m. today at the parking lot at RFK Stadium to decide its next move.

Oberdorfer's rulings clearly were designed to push those involved toward a quick settlement of the complex labor struggle.

On the other hand, he threatened the strikers with fines and even jail sentences if they continued their illegal action. On the other hand, he chastised both Metro and Local 689 of the Amalgamated Transit Union for, in effect, dragging their feet on settling the issue that seems to have caused the strike. They can drag them no longer, because Oberdorfer gave them a nonnegotiable deadline.

He ordered Metro and the union local to tell him by 11 a.m. tomorrow how they are going to get arbitration started by July 31 on the question of whether the strikers automatically were entitled to a 20-cent-per-hour cost of living pay increase. That arbitration must be completed by Aug. 6, he said.

Then, he turned to Metro attorney Peter J. Clano and said, "I hope you come to court Monday on a bus or a subway or that you have a lot more citations (against strikers) to begin trials."

Oberdorfer had just signed an order directing three striking Metro employes - Gary Young, George Goodwin and William Powell - to appear in court Tuesday to explain why they should not be held in contempt for allegedly violating Oberdorfer's no-strike order of last Thursday.

Metro attorneys told the court that all three had continued picketing or other strike activities even after receiving the back-to-work order. One man refused to accept the order, a Metro attorney said.

"We will vigorously carry out the judge's order," Metro general manager Theodore C. Lutz said. "I am pleased he placed the emphasis on an orderly process to resolve this problem."

The "problem" actually began Wednesday when about 90 mechanics from both the subway and bus operations walked off their jobs. Transit service was not affected.

On Thursday morning, however, less than half of the scheduled buses left garages and few drivers completed runs. There was no subway service. Traffic jams were horrible throughout the area.By Thursday afternoon, the strike was all but total and has stayed that way since.

Solving the problem has proven to be tantamount to undoing the Gordian knot. Local 689 officials, according to Metro testimony, have tried diligently to get members back to work. It has become apparent, however, that Local 689 does not control members, and interviews with many strikers showed that they were striking their union as much as they were striking their employer.

Rump groups have cropped up at various bus garages, and rail yards, disavowing the union leadership. Scoggin, for example, was a leader long enough to organize and hire attorneys but then was replaced by Ray.

Because of that kind of confusing leadership question. Metro had to move in court against 123 individuals as well as the union. Lutz has adopted a hard line on discipline and about 180 strikers have been suspended, but not fired.

Lawrence Speiser, representing Scoggin's group, asked amnesty for all strikers, yesterday, but Oberdorfer set aside that request because the strikers have recourse through union grievance procedures and the courts to fight suspension.

Speiser also asked Oberdorfer to modify his back-to-work order and require settlement of the cost-of-living issue by Friday. oberdorfer's first order required Metro and Local 689 to resolve the cost-of-living payment through "expedited arbitration," but gave no deadline.

Attorneys for both Metro and Local 689 attorneys said they have spent their time since the order was issued Thursday "narrowing the issues" for arbitration, rather than concentrating solely on cost of living.

Oberdorfer, who asked many questions of all of the witnesses yesterday, extracted from both Metro and the union local a history of delay in selecting arbitration dates since the contract expired and formal negotiations were broken off April 30.

Early in May, each side picked its own arbitrator, but not until June 21 was a neutral third arbitrator selected, and he will not be available until December or January.

Three weeks ago, according to testimony, Metro and the local began to look for another arbitrator who could handle the matter most expeditiously. One was found who would be available in August. On that basis, Davis told a union meeting Tuesday night that the issue would be settled by the end of August.

It also became clear for the first time yesterday that Metro is holding the cost-of-living issue as a bargaining chip to gain the right to hire part-time drivers, something Metro wants and something the union traditionally fights.

John R. Kennedy, Metro's general counsel and chief labor negotiator, conceded as much in testimony and told a reporter, "I would not want to see [cost of living and part time] separated. "It's a bargaining position . . .

Later, Oberdorfer asked I. J. Gromfine, Local 689's counsel and negotiator, "Why do you have to have the part-time issue (in the arbitration)?"

"I would be happy to drop it," Gromfine said.

Gromfine was no fan of expedited arbitration on cost of living alone, however. During a technical discussion with the judge, he said, "if we go to arbitration and win, [union members] will be happy and will say that's the way to win. If we lose, they will say this union doesn't know what it's doing."

That was after Oberdorfer had said, "The union membership . . . can learn that with the sacrifice of their right to strike,they have the right to expedited arbitration."

Speiser asked union president Davis at one point if he had told members that the cost of living issue would be settled by Friday. Davis twice answered no.

Melvin Brown, one of about 30 striking employes in the courtroom, rushed out and came back waving a piece of paper that was admitted to the members, over Davis' signature, stating that the arbitration would be completed by Friday.

Davis was permitted to change his testimony. "He forgot," Gromfine told a reporter.

No picket lines were mounted at the various garages, but Metro employes were gathered in small groups near them. Only one bus went out - early in the morning.

"Some of the operators want to drive," said a driver at Bladensburg. "But they have to support [the strike]. They're afraid to cross the picket line."

In court, Metro officials said the same thing, estimating that between 70 and 98 percent of those not working would be working if they were not afraid.

Hearing that and other testimony, Oberdorfer told Davis at one point, "This court has broad power [to levy] heavy and progressive fines and even confinement. As hot as it is in this courtroom, it's hotter in the District of Columbia jail."