The Metropliner, the high-speed train that brought some respectability back to passenger rail travel in the United States, is very tired, in need of repair and has never worked in a snowstorm.

Amtrak, which inherited the train and its problems from the defunct Penn Central, is planning to fix the 61 Metroliner cars for about $1 million each - or more than twice what they cost in 1969 dollars when they were built. Among other virtues, the refurblished cars will have the ability to operate in the snow.

"We have to do something to make the Metroliner a premium ride again," said Brian Duff, an Amtrak spokesman. "The new Amfleet equipment is so good that it has diminished the gap between the regular train and the Metroliner."

Recent Amtrak statistics show that for the first nine months of this year, Metroliner ridership is down 8 per cent, but ridership on other Amtrak trains in the Northeast Corridor has increased by 6 per cent.

People are learning that the regualr Amtrak service while about an hour slower between Washington and New York, is $5 cheaper and just as comfortable if not more so.

Furthermore, the extensive renovation of the roadbed now under way between New York and Washington is delaying all trains in the corridor and the Metroliner's on-time performance is wretched.

In August, for example, only 3 Metroliners out of 10 were on time, but seven out of 10 other Amtrak trains between Washington and New York met their schedules.

The Metroliner equipment itself has never been as reliable as railroad officials would like or expect. At one time, as many as 18 of the Metroliner's 61 cars - 30 per cent - may be out of service for one reason or another.

Furthermore, in the almost nine years that the Metroliners have been in operating service, they have never received a major overhaul and they need it. Each car now was traveled an average of about 1.2 million miles.

And in the early 1980s, the North-east Corridor trackled and station improvement program is scheduled for completion and Congress expects Amtrak to provide Washington-to-New York train service in 2 hours and 40 minutes, including fire stips. That is 19 minutes faster thant he present scheduled Metroliner running time.

Metroliner cars, like those on the Washington Metro subway, are self-propelled: there is an electric motor on each axle that provides the power to move the train.

Amtrak's long-range plans call for locomotive-pulled passengers cars, but Amtrak has decided it will need both types to provide the high-speed train service that the Northeast Corridor improvement program expects.

A new Metroliner car would caost about $2 million in today's dollars, according to Robert A Day. Amtrak's director of rolling stock acquisition. For half that the Metorliners can be refurbished along the lines that were suggested in a special study the Federal Railroad Adminstration commissioned to find why the Metroliners did not work as well as they should and to determine what could be done to fix them.

Four Metroliners - two with General Electric motors and two with Westinghouse motors - were pulled out of service, studied, and rebuilt. The result is a car that looks a little different than the other Metroliners but runs better.

Experience with the four rebuilt cars shows cut almost in half, that the cars have been available for service 95 per cent of the time instead of 80 and that there has been dramatic reduction in the number of times the car fails while actually on the road.

The reason it looks different is because s significant chunk of electrical apparatus - called brake resistor grids - has been placed on top of it where it is encased in a medal box.

The braking system used on the Metroliner generates significant amounts of electricity that are dissipated as heat in the resistor grids. While those grids were under the car, the heatr they gave off singed insulation and generally fouled up other under-car components that had to be there.

Another big problem is that the intakes that are supposed to bring cooling air into the under-car components are also located under the car and easily fouled with dirt and debris that is sucked up from the roadbed.

In a snowstorm, particularly one invoving light, dry, blowing snow, the intakes close, overheating occurs and everything stops.

"It really got kind of embarrassing," said M. Clifford Gannett, chief of the passenger equipment division of the Federal Railroad Administration. "When there was a heavy snowstorm they have to roll out the GGls to pull the Metroliners." The GGls are the famous double-fronted electric locomotives that have been the workhorse of northeast railroading for more than 40 years. But they only go 80 miles per hour; the Metroliners are supposed to go well over 100 m.p.h.

With the resistor grids on top, where they dissipate their heat into the air rather than into the train works, and with the air intakes improved for the other under-car equipment, the medified Metroliners will theoretically run well for many years to come.

Day, the Amtrak rolling stock man, said that 16 Metroliners are scheduled for refitting in the current fiscal year. "The only thing holding us back is money," he said in explaining why more will not be done immediately.