Federal Parole Commission hearing examiners have recommended that former Maryland Gov. Marvin Mandel serve the full three-year prison term for his conviction on political corruption charges.

Mandel, who began serving his sentence at a federal prison in Florida in May, had applied for parole in mid-June but, according to informed sources, was told this week that hearing examiners thought he should serve his term "to the expiration."

A source close to the case said the recommendation was highly unusual for its severity. The decision, which was not made public by the parole examiners, is subject to review by the full U.S. Parole Commission, but one source said it appeared that the recommendation "came down from the top." It was not immeidately clear on what basis the hearing examiners made their decision.

Similar recommendations against early parole were also made regarding the appears by Mandel codefendants W. Dale Hess and Harry W. Rodgers, according to sources. No recommendation was offered in the parole request of another codefendant, Irvin Kovens, who has been hospitalized after a recent heart attack.

Mandel and Rodgers learned of the recommendation on Wednesday, in a face-to-face meeting at the Eglin (Fla.) Air Base prison camp with the two hearing examiners, according to sources. Hess, who is serving his time at a federal prison camp on the air base at Maxwell, Ala., was told Thursday.

Mandel's conviction in August 1977 was the first of an incumbent state governor in 43 years. He and his codefendants had applied for parole shortly after they began their sentences. As first offenders, they technically were eligible for parole immediately.

Mandel, Rodgers, Kovens and Hess appeared before the hearing examiners for the first time in July, at their respective institutions. But on Aug. 14, a regional parole commissioner in Atlanta declined to rule on their requests. Instead, he forwarded the requests to the full commission in Washington, saying the case involved too much "national or unusual attention" to be decided by one commissioner.

Later last month, the national commission requested additional information about the case from the U.S. Attorney for Baltimore, Russell T. Baker Jr. With Baker's response in hand, the process resumed.

"Baker apparently did his job, as any good prosecutor would," said one source in speculating that Baker's information weighed heavily against granting a parole to the ex-governor and his friends.

Since his incarceration on May 19, Mandel has been working in the prison's clothing department, teaching a course in current events to his fellow inmates, and pitching for one of the prison's softball teams.

Mandel and his three codefendants originally were sentenced to four years in prison, following their convictions, along with two other men, on federal charges of mail fraud and racketeering. But the trial judge, U.S. District Judge Robert L. Taylor of Knoxville, Tenn., reduced their sentences after they lost a two-year battle to have their convictions overturned.

Also convicted were William A. Rodgers, Harry's brother, who is doing public service work in Baltimore for one year, and Ernest n. Cory jr., an attorney who was disbarred after conviction, but given a suspended sentence. a

Kovens, 61, who had a history of heart trouble was hospitalized on Aug. 28 at the air base hospital at Eglin.Another inmate said Kovens was alone in his cubicle in the modern prison when he fell to his knees, popped a nitroglycerin pill into his mouth and called for help.

Mandel and his codefendants were convicted by a federal court jury in Baltimore, which was told that the governor had accepted lavish gifts from his friends in exchange for his help on legislation benefiting them in connection with their secret purchase of the rundown Marlboro Race Track in Prince George's County. (The track was the scene of a major fire earlier this week.)

Mandel, a Democrat, was the second consecutive Maryland governor to run afoul of the law. His Republican predescessor, Spiro T. Agnew, resigned as vice president after the same federal prosecutors built a case of corruption against him.