The Reagan administration's proposed sale of government loans to help reduce the federal deficit has run into difficulties and will not produce the $5 billion in revenues Congress counted on this year, according to administration officials.

Two-thirds of the way through fiscal 1987, the agencies in the program have yet to sell a single government loan to the investment community.

"Yes, it is behind," said Joseph R. Wright Jr., deputy director of the Office of Management and Budget (OMB) and the leader of the effort. "But we are not pushing it until all the problems are resolved. I'm not about to make a mistake and jeopardize all of credit reform."

The Farmers Home Administration, whose loans were supposed to get the governmentwide program started, has yet to schedule its first offering.

The Veterans Administration -- which is not part of the $5 billion effort -- had tried to sell $84 million in housing loans in a "trial run," but canceled its sale when buyers offered to purchase the loans for as little as 15 cents on the dollar.

The Federal Housing Administration abruptly canceled a sale of 306 low-income housing mortgages on the day of the sale in April after Congress protested that low-income tenants were not protected.

Issues such as this cloud the loan asset sale program, and something that Congress saw as a budget-saver remains primarily a gleam in the eye of OMB Director James C. Miller III.

The administration's loan asset sales program, begun as a $1.5 billion pilot project and accelerated by Congress into a $5 billion deficit reducer, is months behind target and mired in legal, technical, logistical and policy questions.

House Budget Committee Chairman William H. Gray III (D-Pa.) has questioned the loan-sale idea from the beginning, calling it "artificial deficit reduction that provides no permanent relief for the deficit headache."

Others have called it a "national yard sale."

Many loan managers within the bureaucracy also have had doubts about the program. "The reason we have made these loans is that nobody else would," one loan manager said. "If there were an opportunity to make money on them, somebody would already be doing it."

But OMB has pushed the loan sales on four grounds: philosophical, managerial, informational and budgetary.

Philosophically, the administration believes the government should not be making many of the loans. "Why compete with the private sector?" Wright asked.

Miller said selling the loans will reveal their true worth and also reveal that many of them are highly subsidized. OMB says making them subject to final sale -- without recourse -- is the only way to assure that the government does not get all the risk and the investment community all the profit.

Former OMB director David A. Stockman used to regale people in the loan-sale battle with his snake in the watermelon theory. According to one official, Stockman would explain how the government never knew where the snake was and unless it sold its loans federal officials would never know when loans might go bad and "bite."

The General Accounting Office, in a study for Government Operations Committee Chairman Jack Brooks (D-Tex.) said that OMB's insistence that loans be sold without recourse would "adversely affect" their marketability -- which is why the VA debacle on April 14 has reverberated throughout the agencies.

For many years, the VA has been routinely selling loans to investors and getting normal market rates for mortgages. But the loans have been made with the promise that the government would buy back any that went bad.

The VA was not required to make a "nonrecourse" sale this year, but promised the OMB it would try one in preparation for 1988, when such terms will become mandatory.

Wall Street was extensively consulted and the offering was heavily advertised. But the sale "just didn't come off real well," said Raymond L. Brodie, assistant director of loan management for the VA. Many of the mortgages were from Texas and other areas of the Southwest hard hit by the decline in the oil industry.

Two bids were for 15 cents on the dollar, and "not serious," according to congressional aides. The other bid, ranging from 60 to 67 cents on the dollar, covered only $8 million of the $84 million offered. The VA decided to cancel the sale.

Although loan sales to the public have proven to be much more time-consuming than predicted, two agencies -- the Department of Education and the Export-Import Bank -- apparently will meet their revenue goals under the loan sales programs in 1987 by allowing borrowers themselves to "prepay" their loans -- that is, pay them off early at a discount.

The Education Department already has received $256 million through this method, offering the loans at a typical discount of 37 percent. This means that the borrower pays only 63 percent as much as he or she would have if the loan were paid off on its original terms. But the government gets the money right away, rather than 30 years from now.

The Export-Import Bank already has made its $1.5 billion goal, according to the Congressional Budget Office.

The Small Business Administration later this year also plans to allow thousands of original borrowers to prepay disaster home loans that were made in denominations of $5,000 or less.

When the OMB announced its loan-sales program late last year, there were optimistic predictions for sales of about $1 billion in rural development loans made by the Farmers Home Administration early in 1987. Today, FmHA spokesman Ron Ence said, "We have a July or August timetable." Other agencies say the sale has proven to be so complicated that the FmHA will be lucky to squeeze in its first offering before the fiscal year ends Sept. 30.

"Our pilot project was originally to yield $1.5 billion," OMB's John F. Donahue said. "It was intended to establish an apparatus for sale to the public . . . . No one is surprised at what we are finding at all. It is just that we have a lot of work to do."