During the preseason Calvin Hill visited the training camp of the Baltimore Colts as a free agent, trying to find work.

Yesterday at Memorial Stadium Hill did a job in his hometown, but it was against his might-have-been employers. The big running back caught three touchdown passes to help the Cleveland Browns register a 45-24 victory over the defenseless Colts.

Brown quarterback Brian Sipe had his finest day as a pro, completing 15 of 22 passes for 309 yards and four touchdowns. But the spirit-shattering scoring catches by Hill played as large a part in handing the Colts their seventh loss in 12 games to virtually snuff out Baltimore's already-slim playoff hopes.

"I'm glad to be able to make a contribution to the team," said Hill. "That's what I like about playing with Cleveland - getting a chance."

Hill left the Washington Redskins early in preseason, apparently disgruntled over his lack of playing time.

The Colts had even more reason to be disgruntled yesterday as they watched Sipe complete his scoring tosses to wide-open receivers. By half-time Sipe had passed for 198 yards to exceed his per-game average by 33 yards.

"Maybe the Colts are not a good team unless we're hitting on all cylinders," said Baltimore Coach Ted Marchibroda. "The defense had been playing well recently until this game."

But in "this game" the Colt defense gave up 480 yards. Sipe completed seven passes of at least 20 yards.

"We had them on the run but we let up," said Marchibroda. "I guess we thought we had them a little too early."

The Colts took a 10-0 lead on Don McCauley's two-yard run that capped a 75-yard first-quarter drive and Toni Linhart's 23-yard field goal in the second quarter. The Browns then scored 31 straight points.

Hill got things started for Cleveland in the second quarter when he hauled in a 53-yard touchdown pass-run. Hill had come out of the backfield from the right, cut toward the left side of the field and caught the ball in a different time zone from the nearest Baltimore defender.

"It was a third and five and we just wanted enough for a first down," explained Sipe.

The Browns struck for their second touchdown on their next possession. A 48-yard Sipe-to-Reggie Rucker pass was the highlight of Cleveland's fourplay, 56-yard march that ended with Mike Pruitt's one-yard plunge for a 14-10 lead.

A 24-yard punt return by Ozzie Newsome and Sipe's 17-yard pass to Rucker set up Don Cockroft's 45-yard field goal which gave the Browns a 17-10 halftime lead.

Hill was again the culprit when the Browns victimized Baltimore midway through the third quarter. With Sipe sneaking 19 yards on third and seven at one point, the Browns drove 77 yards on their first possession of the second half.

On third and three from the Colt 37, Hill beat Colt linebacker Derrel Luce on a streak pattern for a 24-10 advantage. The 227-pound running back dragged Luce the final four yards into the end zone.

"The oldman can still run a little bit," said Hill.

"The Colts were biltzing on that play, and I guess Calvin surprised them by not staying back there to help out on the blocking," said Sipe. "I knew if he could get past the line of scrimmage we had something."

Cleveland continued to pile it on with the defense taking its turn. On third down with Baltimore on its eight, wide receiver Roger Carr ran a sideline pattern and slipped after making contact with cornerback Oliver Davis. Davis stepped in front of the prone Carr, picked off Bill Troup's pass and sprinted down the right side-line for a 29-yard scoring return and a 31-10 Cleveland lead.

Troup, who otherwise had an excellent day passing (24 of 38 for 296 yards), capped a 64-yard drive with a 24-yard touchdown toss to Carr to reduce the deficit to 31-17 with 4:10 left in the third quarter.

Baltimore had a chance to draw even closer after Doug Nettles recovered a Cleveland fumble on the Colt 23 late in the quarter. But McCauley dropped a third-down pass in the snd zone and Troup was sacked trying to pass on fourth down.

'Hill's 23-yard scoring reception and Rucker's 25-yard touchdown catch ended the scoring for the Browns. They were sandwiched around Troup's two-yard touchdown pass to tight end Mack Alston.

Colt owner Robert Irsay, who earlier in the week threatened to sue every league official, reportedly vowed to fire all the Baltimore coaches except Marchibroda after the game. Irsay later recanted.