INDIANAPOLIS -- Longtime assistant coach Howard Mudd has decided to walk away from football just two days before the Indianapolis Colts open the season at the Los Angeles Chargers.

Coach Frank Reich made the announcement Friday.

The 77-year-old Mudd came out of retirement six months ago and accepted the title of senior offensive assistant, working primarily with new offensive line coach Chris Strausser. Mudd worked for seven NFL franchises from 1974 through 2012 before retiring.

But Reich said that over the past week, Mudd started indicating he might be ready to leave the game again. He previously worked for the Colts from 1998 through 2009, when he helped teach Reich the nuances of run blocking and pass protection.

"He was all-in; it was tremendous in every way," Reich said. "He had a lot of energy, passion, a lot of knowledge and a lot of experience in those meetings. It was a lot of fun for our guys, especially our younger guys to get a chance to rub shoulders with Howard."

Mudd wasn't just a successful coach.

He spent seven years in the NFL as a player with the San Francisco 49ers and Chicago Bears. The former offensive lineman was selected to three Pro Bowls, twice to the All-Pro team and won one Super Bowl ring -- with Indy following the 2006 season. Mudd also was a member of the NFL's 1960s all-decade team.

But those who played for the motorcycle enthusiast and watched him drive around the field in faster than normal golf carts enjoyed learning from him.

"They really harp on the fundamentals and do a great job teaching," All-Pro left guard Quenton Nelson said in May when asked about the two new line coaches. "They are very detail-oriented and what they're teaching -- I feel like I have already seen results in myself and my teammates too. So it has been awesome being coached by them, and they're doing a great job."

Mudd's departure is the second surprise move in less than two weeks. Andrew Luck retired abruptly Aug. 24 following a preseason loss to the Bears.

"He was really physically, I thought, in great shape and his mind is still as sharp as ever. Man, that guy's mind is unbelievable," Reich said of Mudd. "I was able to kind of talk him out of retirement to come and help us make a transition. His contribution over the last six months has been tremendous."

Game notes
Reich also said defensive end Jabaal Sheard (knee) and backup running back Jonathan Williams (ribs) would not play Sunday. ... Backup defensive end Kemoko Turay is listed as questionable with a neck injury. ... The Colts reached injury settlements with receiver Penny Hart and cornerback Shakial Taylor. The move allows them to sign with other teams.