The Metro board voted yesterday to rebuild more than 600 aging buses rather than buy new ones -- a move Metro officials say could improve the reliability of bus service in the 1980s.

The idea is to avoid a repeat of troubles like those Metro had with 115 General Motors "advanced design buses" delivered in 1979 and 1980. The sleek vehicles with tinted windows have been criticized as prone to breakdown, hard to repair and extravagant with fuel.

Rehabilitation costs around $65,000 per bus, something less than half the price of a new one, and entails stripping it down to its chassis and rebuilding engine, sides, floors and interior. Yesterday, the board gave the go-ahead to seek a contractor to rehabilitate 260 buses initially, with the others tentatively to follow by the mid-1980s.

Metro operations chief Theodore Weigle predicted the program would improve service by reducing breakdowns-- the mid-route failures and air-conditioner shutdowns so familiar to those who ride Metro's 2,000 buses. "The buses that we're rebuilding are the ones that we know the best and that traditionally have performed the best," he said.

Weigle also said attention will be focused on the shoddy maintenance that contributes to poor service.

Metro has settled on 617 GM "New Look" buses aged between 12 and 17 years. As the job is completed in phases into the mid-1980s, it will allow transit planners to transfer to the reserve fleet many of Metro's 608 buses made by AM General. As a group they are considered the least reliable, Weigle said.

Metro currently has no experience in operating rebuilt buses. As now laid out, the program would be the country's largest ever. Weigle said that if the rebuilding is planned and monitored closely, Metro could be sure of getting quality work that would increase each bus' life by about seven years.

Federal grants account for about 80 percent of Metro's bus capital budget. When these grants are used to buy new buses, regulations require competitive bidding, with the low bidder winning the contract. That means that Metro cannot select which make of bus it gets.

Metro officials say privately that they do not want more GM advanced design buses. They are more complex than older models and require costly new training for mechanics and spare parts. Replacing basic components such as transmissions takes twice as long as with the old GM buses, a staff report said.

Metro is also wary that a bid might by won by the only other major U.S. manufacturer, Grumman Flxible. Last year, with widespread publicity, its versions of an advanced design bus were found to be developing body cracks, resulting in the recall of nearly 3,000 buses.

Transit systems across the country are experiencing similar problems with the new generation of U.S.-manufactured buses. Based on designs from the late 1960s and early 1970s when oil was cheap, the buses are fuel hogs by today's standards and are too costly to operate for financially strapped transit systems.

Improving service on buses is a critical issue for Metro because they still carry the bulk of the system's riders and account for most of the complaints.

Metro's consumer relations office told the board yesterday that in September, Metro logged 891 formal complaints about its bus service, with over half of them relating to buses arriving late or not at all or failing to pull over at a stop. Rail complaints totaled only 55, with rude personnel and fare gate problems being the most common subject.

In other Metro developments:

Senate and House conferees settled on $290 million in federal construction funds for Metrorail this fiscal year. That is $25 million less than Metro had been counting on for the first year of a four-year building program.

The Metro board was informed that bids will soon be solicited for development of a multimillion-dollar commercial complex at the King Street station in Alexandria, scheduled to open for service next year.

The board approved experimental rush-hour bus service between the Pentagon rail station and the Park Center office building in Alexandria to accommodate U.S. Department of Agriculture personnel being transferred to the office building. Three trips in the morning and three in the evening are scheduled to begin in December.

The board approved a resolution to change the name of the Alabama Avenue subway station, located on the unbuilt Green Line, to Congress Heights.