The Baltimore Orioles, who have made everything look easy for two weeks, had their five-game winning streak stopped in the cool, dark Kingdome this afternoon.

Barely.

Seattle Manager Dick Williams had to use three pitchers to protect a six-run seventh-inning lead, and they succeeded by the thinnest of margins as the Mariners held on for a 7-6 victory before 14,344.

What's more, the Orioles left 10 runners on base, six of them on second or third. After Seattle's 7-1 lead had all but evaporated and the Orioles had left the tying run on second base in the ninth, one hardly could tell which team had won.

"When you've got that kind of lead, you've got to go after hitters," Williams said angrily after the game. "Just go out there and throw strikes. Jeez, a six-run lead. I don't know what our problem is."

In the other clubhouse, Orioles starter Storm Davis (4-3), knocked around for nine hits and seven runs in five-plus innings, said, "Hey, we'll just put this game behind us and go on. We've got to keep our heads up because we're playing well right now."

In losing for only the third time in 16 games, the Orioles (25-17) got Rick Dempsey's second home run in as many games and three hits apiece from Cal Ripken and Eddie Murray.

Trailing, 7-1, after six innings, they almost got more than that, sending eight men to the plate in the seventh, scoring four times and leaving a man on second.

Dempsey led off with a homer to make it 7-2. John Shelby's triple combined with an error on center fielder Johnny Moses made it 7-3. Williams pulled starter Mark Langston (3-4) and went for reliever Peter Ladd, who faced five hitters and allowed three of them to reach base.

The first batter Ladd faced was Lee Lacy, who doubled, and after Ripken grounded out, Murray singled and stole second. Mike Young scored them both with a double to make it 7-5, and with Young at second, Orioles Manager Earl Weaver sent up pinch hitter Fred Lynn.

Williams countered with left-hander Matt Young, who had allowed a grand slam to Lynn Friday, but this time Young got Lynn on a called third strike to end the seventh.

"That's the game right there," Lynn said. "I'm just trying to do anything I can to get on base because Floyd Rayford is coming up behind me, and he'd hit the ball hard."

Lynn was upset about a couple of elements of his at-bat, one being that what he believed to be a checked-swing was called a swing for the second strike. Then came the third strike.

Lynn walked back to the dugout and yelled, "Did you see the replay?" at home plate umpire Dave Phillips. Phillips looked over his shoulder and threw Lynn out of the game. "That's the first time I've been thrown out since about 1978," Lynn said.

Still, the Orioles had a chance in the ninth when Murray, Juan Beniquez and Young had two-out singles to score the sixth run, and Matt Young had to face Alan Wiggins with the tying run at second. Wiggins grounded a ball up the middle that shortstop Spike Owen lunged for, fielded and flipped to second baseman Harold Reynolds to end the game.

"Some of their hits didn't go where our books said they'd go," Weaver said, "but I'm sure during our streak, some of our hits haven't gone where they were supposed to go."

Davis' pitching line looked much worse than the results. The Mariners got three runs off him in the third inning, two in the fourth and two in the sixth.

Most of their offense was a result of two doubles by Reynolds, who came into the game hitting .167; a triple by shortstop Owen, a .225 hitter; a triple by Moses, who was called up from Calgary recently; and Jim Presley's sixth homer of the year.

"I didn't come out of the bullpen with bad stuff, and I didn't go down with bad stuff," Davis said. "They just hit 'em where we weren't. I've won with a lot worse stuff, but you still have to give our guys credit for battling back."

Davis' trouble started in the third when Owen led off with a triple over Shelby's head in center field. Reynolds then lined a double to right, and Moses blooped a long, lazy fly ball down the right field line.

Unfortunately for the Orioles, they were playing Moses to hit it toward the left side, and the fly ball fell just inside the foul line for a triple.

He ended up scoring when Lacy's relay throw got away from first baseman Murray.

That made it 3-0, and it went to 5-0 in the fourth when Dave Henderson singled and Presley homered.

Then in the sixth, when Henderson and Presley led off with singles, Weaver brought in reliever Nate Snell, who pitched the final three innings but not before allowing Davis' final two runners to score on another double by Reynolds.

Those runs set up the Orioles' belated rally, and they again dropped 3 1/2 games out of first.

"I'll take six runs and 15 hits every game," Weaver said, "but it's tough when you get that many and lose."

The Orioles have homered in 12 straight games . . . In his last 11 games, Murray has gone 22 for 43 and raised his batting average from .230 to .308. . . The Orioles flew to Oakland and will begin a two-game series with the A's Wednesday.