Washington — When Harry Truman left office, he climbed into his car and drove his family back to Missouri. He was strapped for cash, because he had to spend half his income on post-presidency duties such as handling phone calls, answering mail, and meeting requests for speeches. After he left the White House, the present system of pensioning former presidents was instituted.
Mr. Truman's financial problems were like those of some other ex-presidents. Friends wanted to hire him, make him vice-president of a big corporation. But he said, ''I would never lend myself to any transaction, however respectable, that would commercialize the prestige and dignity of the office of the presidency.''
Were they interested in Harry Truman, he wondered, or the former president of the United States? To relieve such embarrassment, the presidential pension program was instituted. And the unwritten rule evolved that every former president has a library built in his honor.
Now there are some who say things have gotten out of hand, and there's a congressional move to cut back.
It's not just the cost of pensions for former presidents or Secret Service protection for them and their families - let alone free postage - that bugs some critics. It's the overall expense of staffs and assistants. The initial cost of
''Are we now in danger of creating an 'imperial ex-presidency?' '' asks Sen. William V. Roth Jr. (R) of Delaware.
In England it might all be simple; they could find seats in the House of Lords, or be absorbed in the Cabinet or in the opposition's shadow government. Here, the Senate Governmental Affairs Committee is holding hearings on future policy, with a draft bill under debate.
''I think the American people want former presidents to be treated with dignity and grace. But dignity and opulence should not be confused,'' says Senator Roth, chairman of the committee. ''I think the significant thing is that the level of these benefits has grown tremendously over the last two decades.
What to do with America's ex-presidents? The subject has been argued for two centuries. Many feel they are among the nation's most precious assets. They give dignity and continuity much as a monarchy does, it is said. They rise above the battle. They are perhaps still partisan, but their first view is national. They continue in public life long after leaving office.
One question now debated is the role of presidential libraries. There are seven so far. They act as a repository for presidential papers and a museum to chronicle the life and events of the time. There is a Presidential Libraries Act , but it does not provide specific standards for the General Service Administration in approving such libraries. Generally a substantial part of the funding comes from the Treasury.
The pending bill, supported by Senator Roth and, in part, by Sen. Thomas F. Eagleton (D) of Mo., the minority leader of the committee, would standardize this.
The new structure must be appropriate for its surroundings; no replica of Washington monumental design in a town like Independence, Mo., or Plains, Ga. The proposal would set a limit of 40,000 square feet (including museum space) on the size of the facilities. The average size of the existing presidential libraries is 64,000 square feet, of which 17,000 is museum space. Several newer libraries, however, are stretched to 100,000 square feet.
Ex-presidents now automatically get a federal pension of $69,630 a year for life. They generally live quieter lives. The example of John Quincy Adams was not followed by others: After being president from 1824-28, his Massachusetts district sent him to the House of Representatives, where he served notably from 1831 to 1848.
Some ex-presidents had trouble with finances. Grover Cleveland became a director of a life-insurance company, and Calvin Coolidge, for a combination of reasons, wrote a syndicated column. Congress finally passed a presidential-pension bill in 1954.
For fiscal 1982, $11.7 million was budgeted for former presidents' Secret Service protection. The costs of pensions, staff, and offices was $325,000 for Richard Nixon, $318,000 for Gerald Ford and $374,000 for Jimmy Carter.