The Montgomery County Council yesterday urged the Metro board of directors to employ the least expensive of five proposed construction plans in building the controversial Wheaton-to-Glenmont Metrorail line.

At the same time, the Council voted to send letters to County Executive James P. Gleason, Maryland Transportation Secretary Herman Intemann, and U.S. Transportation Secretary Brock Adams in an effort to win release of $325 million in Metro construction funds now being withheld by intemann at Gleason's urging.

"We're writing letters to everyone involved in hanging up the money to tell them to quit hanging up the money," said Montgomery County Council President John L. Menke yesterday.

County officials said they are confident that the Metro board will endorse the same construction proposal at its Thursday meeting. The federal government has yet to guarantee that it will finance the bulk of the construction for the Glenmont line.

The construction proposal adopted by a 6-to-1 vote of the Council yesterday involves the building of a deep tunnel line with tube-line stations at Forest Glen and Wheaton. The proposal would cost $347 million - $25 million less than the original plan for the line according to amemo written by Metro general manger Theodore C. Lutz.

The deep-tunnel proposal would be the least disruptive of Georgia Avenue traffic, the major thoroughfare followed by the Metro Red Line according to Gleason, who also favors the deep-tunnel plan.

Gleason had insisted that the $325 million not be released until the U.S. government guaranteed that the 4.5 mile stretch of the Metro Red Line between Silver Spring and Wheaton would eventually be built.

Council members insisted yesterday that the money should be released regardless of whether the Urban Mass Transportation Administration makes such a commitment.

"The Shady Grove line can't be built without the funds," Menke said. The withholding of the funds has resulted in the suspension of all new Metro construction throughout the Washington area.

Gleason's action "was a tactic," said Council member Ester Gelman. ". . . a very effective tactic. I think it worked. If Montgomery County is holding back (the funds) then (the federal government has) to say there is something urgent about this line."

Most of the other Council members disagreed. Council member Norman Christeller said, "It was counterproductive and it hurt the other jurisdictions. Gleason's unilateral action, and then his saying to us 'I don't have to justify it,' is no way to act in this government."

Council member Jane Ann Moore, whose vote was the only dissenting one on the issue of the construction plan and the sending of the letters, said she was not convinced the line was "cost-effective". "Without the inclusion of (projected) riders hip figures . . . there is no way I can rationally conclude that this line deserves the support of citizens' tax dollars," she said in a statement she released yesterday afternoon.