A naval air base in California has paid Grumman Aerospace Corp. $659 each for aircraft ashtrays and $404 apiece for socket wrenches while watching the price of landing-gear clamps increase more than 2,500 percent over a 16-month period, the Navy said yesterday.

Cmdr. Tom Jurkowsky, spokesman for the Pacific Fleet Naval Air Force, said the Navy is investigating "the causes of these apparent pricing irregularities" and trying to assess the value of the items in question.

Jurkowsky said he did not know how many ashtrays, wrenches and clamps were purchased by Miramar Naval Air Station near San Diego or why Navy procurement officials failed to challenge the billings, which go back to January 1982.

"On the surface, there doesn't appear to be justification for those prices," he said.

Pentagon spokesman Michael I. Burch, saying there is "no excuse" for the purchases, said "an immediate payment will be obtained" from Grumman or the amount will be withheld from its regular contract payments.

Burch said Navy officers who authorized the purchase will be disciplined and, if investigators find there was "ignorance or disregard of regulations, dismissals may be warranted."

A spokesman for Grumman, the nation's 11th-largest defense contractor, with $2.4 billion in sales to the Pentagon last year, said the company was unable immediately to explain the billings but would consider reductions "if they are out of line."

Prices for the three items were uncovered recently by an investigator for the House Government Operations Committee who was examining procurement records at Miramar and alerted the Pacific Fleet command.

They are the latest entries in the Pentagon's collection of extraordinary billings by defense contractors for spare parts. Items publicized earlier include $7,400 for a 10-cup coffee pot for the C5A cargo plane, $16,571 for a small refrigerator to hold lunches and soft drinks for the crew of the P3 submarine-chasing airplane, and $640 for a toilet-seat cover, also for the P3.

"You could buy these things for a fraction of what the Navy paid for them," Rep. Jack Brooks (D-Tex.), chairman of the Government Operations panel, said of the ashtrays, wrenches and landing-gear clamps purchased by Miramar. "It's an outrageous waste of money."

Jurkowsky said the ashtrays, priced at $659.53 each in February 1983 and April 1985 billings, are designed for Grumman's E2C electronic surveillance aircraft at Miramar. The 4-by-4-inch chrome receptacles are inserted into a frame built into the plane's bulkhead so that they can "withstand certain stresses at high speeds," he said, adding, "It's not like going down to your department store and buying plastic ashtrays."

The socket wrench, for which Grumman charged $404.25 in a June 1984 bill, is a metal tube the height of a pack of cigarettes and designed to adjust ejection-seat bolts on F14 fighter planes.

Jurkowsky said Navy investigators also are looking at the steep price increase for the "ground lock," a clamp attached to the E2C's landing gear to secure it. In January 1982, Grumman charged $102 per clamp; by April 1983, however, the item cost $2,710.

None of the prices was challenged despite an investigation into Grumman's pricing formula, Jurkowski said.

In that investigation, Miramar found that Grumman as much as tripled its prices above the catalogue listing for out-of-stock items, he said. He cited the case of an aircraft retaining pipe sold by Grumman for $1,199, compared with a list price of $380.

Jurkowski said the Navy paid higher prices to assure that its aircraft remained "mission capable" only to have auditors question the costs late. CAPTION: Picture, This is the type of E2C plane ashtray for which the military paid $659.