Tom Rowe and Jack Lynch scored third-period goals tonight and Dennis Maruk tied a Washington assist record of 46 as the Capitals surged past the Vancouver Canucks, 6-2, to snap a seven-game winless streak.

The Capitals had not won since Feb. 15, when they defeated the Colorado Rockies, 9-3, in Denver. Since then, Washington had lost five and tied two.

The Capitals took a 1-0 lead in the first period on rookie Paul Mulvey's first goal since Oct. 25. Although the Canucks had a 10-7 shooting edge over the first 20 minutes, their fans were displeased, booing frequently and cheering loudly only once, when the announcement was made of one minute to play.

The goal was set up by Rolf Edberg, who checked another Swede, Vancouver's Lars Lindgren, off the puck behind the Canucks' net. The puck squirted to Mulvey, who skated in front and flipped a backhander over flopping goalie Gary Bromley. It was Mulvey's fourth goal of the season, but his first in 31 games.

Washington goalie Gary Inness made some excellent saves, covering for teammaters' errors. Defenseman Gord Lane passed from behing his net to the Canucks' Thomas Gradin in the slot, but Inness blocked Gradin's shot. When Robert Picard lost the puck to Vancouver's Rob Tudor in front of the Washington goal, Inness came out and Tudor slid the puck through the crease behind him.

The Capitals' high-scoring line of Greg Polis, Dennis Maruk and Tom Rowe applied considerable early pressure. They did not score, however, as Rowe fumbled a pass in front and Maruk shot wide from close range. When Polis was shaken by a Tudor check, Edberg moved to left wing in his place.

Vancouver was playing short, with defesemen Jack McIlhargey serving a one-game suspension for acquring his third game misconduct of the season Wednesday night Another defenseman, Harold Snepsts, who played so well in Vancouver's 5-1 victory at Capital Centre Feb. 3, was dressed for insurance purposes while nursing an injury.

Mulvey, who lives in Merritt, British Columbia, added another goal and Edberg scored two as Washington built a 4-1 margin in the secone period.

Vancouver tied the game at 1:54 as defenseman Bob Manno cut over the blue line, exchanged passes with Gradin and scored from the slot as Bob Sirois barely missed poking the puck off his stick.

Inness made two excellent saves on breakaway opportunities by Brad Gassoff before the momentum shifted to the Capitals.

A fine clearing apss from Rick Green to Maruk started the tie-breaking play, with Maruk spinning after crossing the blue line and feeding Edberg skating into the slot. Edberg connected from 25 feet at 9:06, as Dennis Kearns checked him, for his seventh goal of the season.

Edberg was back at left wing on the line with Maruk and Rowe, Polis having departed after two second-period shifts to ice a sprained right knee.

The fans were booing a lengthy succession of erratic passes in center ice when they suddenly became even more unhappy. Denni Hextall, centering in Edberg's place with Mulvey and Blair Stewart, cut into Vancouver ice and dropped a pass to Mulvey in the left-wing circle. Both Vancouver defenseman, Manno and Kearns, missed checks on Mulvey and hit each other, permitting Mulvey to cruise in for an easy score at 16:38.

The embattled Bromley stopped a Rowe breakaway moments before the one-minute warning, which produced another derisive cheer from the crowd. But before the period ended, Edberg deflected a Picard drive from the left ponint past Bromley for his eighth goal and his first two-goal game in the NHL.

Rowe's record-tying goal came against Dunc Wilson, who replaced Bromley at the start of the third period. After taking a feed from Edberg, Rowe put a good fake on Stan Smyd, then beat Wilson on the strick side from 30 feet at 3:07 for his 25th goal.

Tudor's second NHL goal brought Vancouver within 5-2. Anchored in the slot, he was set up by Gassoff's pass from behind the net at 6:26.

Thirty-two seconds later the Canucks' Ron Sedlbauer was awarded a penalty shot after he was hooked down from behind on a breakaway by Yvon Labre. Sedlbauer became 0-for-3 on career penalty shots when he hit the crossbar with Innes well out to combat an expected deke. It was the 10th penalty shot taken against the Capitals in ktheir five-year history and only two have succeeded.Jim Bedard foiled Montreal's Jacques Lemaire earlier this season.

Jack Lynch, who scored his first two points of the season Wednesday night in Los Angeles, netted his first goal at 7:13, blasting a 50-footer past a screened Wilson. Lynch, who needed knee surgery after suffering a severe injury here Dc. 13, 1977, gave his maribou stork mating dance a few extra twists after this goal.