The Pittsburgh Penguins, who dimmed the Washington Capitals' playoff hopes 18 days ago, put out the lights last night.

Down, 2-0, after 2 1/2 minutes, the Penguins overpowered the Capitals the rest of the way to earn a 6-5 victory at Capital Centre, squeezing the last gasp of playoff breath out of Washington.

The Capitals, behind the eight ball since they got off to a 1-14 start, finished out of the playoffs for an eighth straight year, the only one of the NHL's 21 teams never to enter Stanley Cup competition.

Pittsburgh beat the Capitals for the fifth time in seven games despite the absence of five regulars--injured Mike Bullard, Gregg Sheppard, Randy Boyd and George Ferguson, and flu-ridden Rick MacLeish.

Steve Gatzos, called up from Erie of the American League yesterday, made a perfect pass to another recent farmhand, Jim Hamilton, to start the Penguins' comeback after goals by Lee Norwood and Ryan Walter threatened to turn the game into a rout for the Capitals.

Pat Boutette and Hamilton lifted Pittsburgh into a 3-2 lead before the first period ended, as the Penguins outshot the Capitals, 23-6. The players in white appeared to be burdened by the ghosts of Greg Joly, Mike Marson, Tommy Williams, Bill Mikkelson, et al, as they stood anchored in place watching the Penguins hustle past them.

"It was such a dreadful first period, I just asked our people to give what they had to give," said Washington Coach Bryan Murray. "I think they made an effort, but Pittsburgh played better than we did. They were bigger and stronger and it paid off in two areas, taking the body and moving the puck out of their zone.

"We scored five goals, but we never really controlled play in their zone. And in our zone, they eliminated people on a regular basis. They jammed in a couple from the side of the net, which was a result of being able to stand around in front."

A play early in the second period indicated that the infamous dark cloud was still hanging over the Capitals. On a rebound of a shot by Darren Veitch, Dennis Maruk shot the puck toward a net left vacant by goalie Gary Edwards. Defenseman Marc Chorney knocked the puck down with his stick and, as it rolled on the goal line, kicked it away with his skate.

A power-play goal by Paul Gardner then increased Pittsburgh's lead to 4-2. The Capitals rallied briefly when Bengt Gustafsson's 26th goal, following Bobby Carpenter's steal from Paul Baxter, reduced the deficit to 4-3.

Washington's Greg Theberge was whistled off for hooking a few moments after an apparent icing by Pittsburgh was waved off. The Capitals appeared to benefit from that turn of events when Glen Currie produced a game-tying, shorthanded goal on a setup by Bobby Gould.

With only 14 seconds left in the period, however, Gardner's power-play backhander on Rick Kehoe's feed sent Pittsburgh ahead to stay, 5-4.

With 13 minutes remaining in the game, Gould shot over the net after Currie's pass freed him in close. When play moved to the other end, Rod Schutt scored on a long shot from the left-wing boards, goalie Dave Parro muffing a seemingly easy one.

Murray dug deep with 8:32 left, ordering a measurement of Boutette's stick. It proved illegal and Chris Valentine's 27th goal on the ensuing power play stirred some hopes among Capital faithful in the crowd of 10,057. Darren Veitch assisted to extend his point-scoring streak to nine games, but that was to be the final positive note for Washington.

The weary Capitals hardly threatened during an interference penalty to Peter Lee. For a final note, after Parro was pulled for a sixth skater, Andre St. Laurent shot wide of the empty net and Boutette outskated the Capitals to the puck to wash out a potential icing call.

After a 1-14 start, Washington had drained itself just making a run at the Penguins. Embarrassed, 7-2, by Pittsburgh here on March 10, the Capitals at least this time left with a semblance of self respect.

"It's nice to score 50 goals," said Maruk, a 58-goal scorer who has not seen playoff action in seven NHL seasons, "but I'd settle for 30 goals and a chance to be in the playoffs. I've never known the feeling, but it must be great."

"Any time you're down as far as we were, it makes it tough," said defenseman Terry Murray, playing his 300th NHL game and a veteran of two playoff years in Philadelphia. "We had to win every game and they had to lose every game. When you're that far behind the eight-ball, you want to force and do a lot of different things. And when you force it, it goes the other way."

Tom Rowe made another appearance in a Washington uniform, having been recalled from Hershey yesterday because the Capitals were without Randy Holt and Torrie Robertson, both of whom drew automatic one-game suspensions for receiving their third game misconducts of the season in Saturday night's 4-4 tie with Philadelphia. Holt faces further disciplinary action for his assault on linesman Paul Flaherty. The rest of the Capitals just face another long, long vacation.