Marty Schottenheimer resigned as coach of the Cleveland Browns yesterday, he and owner Art Modell citing irreconcilable differences as tension escalated over several issues.

"It became evident that some of the differences we had, we weren't going to be able to resolve," Schottenheimer said. "We came to an agreement that it was in everybody's best interest that we part company."

Schottenheimer obviously had no chance to win a struggle with Modell, who expressed unhappiness over his team's failure to live up to expectations, Schottenheimer's handling of the offense, and the coach's recent treatment of quarterback Bernie Kosar. Schottenheimer had served as his own offensive coordinator since Lindy Infante left the staff after the 1987 season to become head coach at Green Bay, and Modell wanted that changed in 1989.

Tom Flores, the former Los Angeles Raiders coach with two Super Bowl titles, would appear to be one of the leading candidates to succeed Schottenheimer, according to a Knight-Ridder Newspapers report. At 51, he has been out of coaching since he quit after the 1987 season.

Knight-Ridder talked with Flores' wife in Manhattan Beach, Calif., and was told he was out of town and wouldn't be available for comment until this morning.

Among several others thrown into the rumor mill was Washington Redskins assistant Joe Bugel.

In a meeting between owner and coach yesterday, Modell more or less forced Schottenheimer's hand. Modell said several assistants will not be retained, but did not specify.

"Changes might not be radical, they might be radical," Modell said. "I don't know . . . I must reassess all our personnel -- coaching, scouting and players. I do know this: the Cleveland Browns will not preserve the status quo for 1989."

The Browns, at 10-6, made the playoffs for the fourth straight season. Still, there was disappointment over qualifying only as a wild card in 1988 after demoralizing losses to Denver in the 1986 and 1987 AFC championship games.

Ending two games behind Cincinnati in the AFC Central and losing to division rival Houston at home in the playoff opener ate at Modell.

"What I see out there is the Oilers and Bengals franchises surging ahead and I see us treading water," he said. "Frankly, if I were to handicap next year, we would be the third favorite in the division. That's not good enough."

A lot of the friction was over Schottenheimer's selection of plays. And against the Oilers, the Browns seemed overly predictable near the goal line. Three times he used a run-run-pass sequence; the passes failed and the Browns had to settle for field goals in a 24-23 loss.

Schottenheimer said, "I was frankly satisfied that I did a good enough job" as offensive coordinator.

"That might be his personal perception. I might have a different one," Modell said.

Modell was also disturbed that the coach might have alienated Kosar by admonishing him about standing in on the quarterback-coach huddles on the sideline when he was out injured at season's end.

The owner said he feels Kosar is the only "franchise" quarterback the Browns have had since Otto Graham and "I intend to give him the support he deserves, whether it be {pass} protection, coaching, counseling, wide receivers, whatever."

Schottenheimer, 45, who went 46-31, including playoffs, in 4 1/2 seasons, said he chose not to hire an offensive coordinator because "I frankly thought we would go backwards {after losing Infante}."

A former linebacker, Schottenheimer had been the Browns' defensive coordinator when promoted to replace Sam Rutigliano in midseason 1984. After yesterday's announcement, he said he'd like a chance to be a head coach elsewhere.