Cole (2-4) held the Nationals to one run, three hits and two walks over his seven innings. He struck out three and didn't allow any Nationals player to reach base more than once. Cole extended his streak of quality starts to eight.
Cole hadn't received much run support this season, with the Pirates providing just two runs per nine innings while he was on the mound this year. That contributed to his sub-.500 record despite his sparkling ERA, which he lowered to 2.84.
Bell's 398-foot blast to the seats in right field was his eighth of the season and was the only damage against Washington spot starter Jacob Turner (2-2).
Turner was cruising until he ran into trouble in the sixth inning.
John Jaso walked, Andrew McCutchen hit into a fielder's choice and David Freese reached on a hit batsman before Turner served up a 3-1 fastball that Bell turned into a souvenir.
The Pirates added on in the seventh inning against the Washington bullpen with a McCutchen two-run double and a Francisco Cervelli sacrifice fly. McCutchen finished 2-for-4 with two stolen bases and a run. It was his first multi-steal game of the season.
The only Washington offense came from a Brian Goodwin RBI double in the seventh that scored Daniel Murphy from first base.
Felipe Rivero and Juan Nicasio each pitched a scoreless inning for the Pirates to seal the win.
NOTES: Pirates OF Gregory Polanco was placed on the 10-day disabled list with a strained left hamstring. Polanco injured himself running to first base against Arizona on Sunday and left the game. OF Danny Ortiz was recalled from Triple-A Indianapolis to replace Polanco. Ortiz was hitting .253 in 27 games with Indianapolis. He entered as a sub Wednesday and drew a walk. ... Pirates RHP Felipe Rivero (sore neck) was back in action for the first time since Saturday. ... Nationals RHP Joe Blanton was placed on the 10-day disabled list due to right shoulder inflammation. Blanton was 0-2 with a 9.49 ERA. Washington recalled LHP Matt Grace from Triple-A Syracuse, his fourth recall this season. He pitched a 1-2-3 inning in the eighth.