The Senate, slowly grinding down everything standing in the path of adjournment, voted yesterday to give up a proposed congressional pay raise and drop its campaign to end Justice Department involvement in school busing suits.

But it failed to finish its big omnibus spending resolution that contained the antibusing and pay raise riders before recessing last night, raising doubts about whether Congress can adjourn by Friday, already a week after its target date for quitting.

Voting 69 to 21, the Senate avoided the political embarrassment of aproving a lame-duck pay increase for itself by keeping a salary freeze that applies not only to members of Congress but to 34,000 other top-ranking government officials.

That may not be the last word on pay raises, however. Congressional sources said last night there may be an attempt to resurrect the issue in the Senate today or in a House-Senate conference on the spending resolution, even though the House-passed measure retained the pay freeze.

On busing, the Senate, ducking a recorded vote, swiftly agreed to drop its earlier insistence on busing language that triggered a confrontation with President Carter -- a standoff that could have delayed the possibility of congressional adjournment later this week.

The antibusing forces, anticipating support for busing restrictions from the incoming Reagan administration and consoled by the Senate's rejection Tuesday of fair housing legislation, simply declared victory and withdrew.

"I say again that this battle has been won," said Sen. Jesse Helms (R-N.C.), obligingly declining to ask for a recorded vote that might have prompted the Senate, once again, to go on record against Justice Department intervention in suits to promote desegregation of schools by requiring busing.

The antibusing language was then deleted by voice vote, with only about a dozen senators on the floor.

The antibusing provision, along with the pay raise, had been tacked onto an omnibus spending resolution that Congress needs to pass before it goes home in order to keep many agencies of government, including the big domestic bureaucracies, operating into the new year.

This stopgap funding measure, the second so far this year, is required because Congress has finished action on only nine of its 13 regular appropriations bills for fiscal 1981, which began last October.

Carter vowed last week to veto the so-called continuing resolution of it, like a previously approved appropriations bill for the Justice Department, included the busing curbs. Leaders of both houses said his veto would be sustained, leaving a big chunk of the government without any money to spend after Dec. 15, when existing stopgap spending authority runs out.

It was this adjournment-threatening predicament, rather than any change of heart on busing, that prompted yesterday's retreat, which is expected to win the concurrence of the House for similar reasons of expedience. The House had also approved the antibusing language.

"We're going to hear about this again . . . much is left to be heard on the whole subject," lamented Sen. Lowell P. Weicker Jr. (R-Conn.) as he won his apparently short-lived victory to kill the busing restrictions.

Helms then predicted confidently that Congress, supported enthusiastically by the new Reagan administration, would impose busing restrictions soon after the White House and the Senate fall into Republican hands next month.

Sen. Strom Thurmond (R-S.C.), who will be chairman of the Senate Judiciary Committee next year, said it will be "done just as quickly as it can be done." Added Thurmond: "The Senate has spoken, the House has spoken, the people do not favor forced busing for racial balance."

Helms has said he will advocate, with Reagan administration support, legislation denying federal court jurisdiction over cases involving busing to achieve a racial balance in public schools. This would go considerably further than simply putting restrictions on the Justice Department in school suits.

At the end of the low-key exchange, which climaxed months of acrimonious debate over the issue in the Senate, Helms and Weicker shook hands, smiling. dBut it had an aura of prize fighters entering the ring rather than leaving it, considering that it will all start up again next year.

The defeated pay raise proposal would have increased congressional salaries from $60,662.50 to $70,900 annually, with comparable increases for federal employes at GS Grade 15, Step Five and above.

It had been proposed by Senate Minority Whip Ted Stevens (R-Alaska) and inserted in the continuing resolution by the Senate Appropriations Committee as one of dozens of amendments to a relatively simple stopgap funding resolution adopted earlier by the House.

But it was political poison on the floor, and Stevens was brushed aside even as he appealed for the pay increase for the executive branch alone.

Because executive salaries are tied to congressional pay and Congress is afraid of the political repercussions of raising its own pay, high-level executive salaries have been compressed to the point where an electrical engineer working for the Air Force earns as much as a member of the Joint Chiefs of Staff, Stevens complained. The government can't be run this way any more than "you can run a supermarket at the level of pay of a checker who is putting the groceries in the bag," Stevens added.

But Helms argued there is "no shortage of competent Americans willing to serve the government," adding, "I don't see any loaded buses leaving Washington with disgruntled $50,000-a-year employes."

The Senate also finessed the fact that the spending resolution will probably breach the spending ceiling that Congress adopted only two months ago by simply stating that no money could be spent after the $632.4 billion ceiling is reached. Presumably this would require spending cuts by the Reagan administration or an increase in the budget ceiling, but Congress was clearly in a mood to defer that problem.

"Once again the emperor is parading through here without any clothes on," complained William L. Armstrong (R-Colo.), contending that the action made a mockery of the the congressional budget process.

However, the Senate refused to vote to cut Senate expenditures by 15 percent, as opposed to the 10 percent cut approved by the Appropriations Committee, after several senators complained the larger cut was simply an unrealistic political gesture and, according to Senate Budget Committee Chiarman Ernest F. Hollings (D-S.C.), "economizing to the point of stupidity."

The proposal to cut Senate expenses by 10 percent came from Republicans. The 15 percent reduction proposal came from Sen. Jim Sasser (D-Tenn.), who is up for reelection in 1982. "I don't mind running for office, I've just finished that myself," said Hollings, who then argued that the cut would be unrealistic as well as politically self-defeating in cutting back services that senators can perform for constituents.

In a related vote, the Senate agreed to give up to three months' severance pay to committee staff members who lost jobs because of last month's election, cushioning the blow of defeat even more by approving up to one month's severance pay for senators' personal staffs.

The Senate also showed a reluctance tomake big cuts for executive agencies, refusing, 43 to 46, to eliminate a $78.9 million supplemental appropriation for the Amtrak train system, even though some senators claimed the Carter administration hadn't endorsed the expenditure.

In the pay increase vote, Sen. Charles Mathias (R-Md.) was the only Washington-area senator to vote in favor of raising the salaries.