The Mongomery County Council voted unanimously this week to support expansion of the county Head Start program for disadvantaged children to include 3-year-olds. The program now is limited to 4-year-old youngsters.

The approval of County Executive James P. Gleason is required before the Department of Health, Education and Welfare will grant the $71,000 in Head Start funds for which Montgomery County is eligible.

Gleason has already said he is opposed to the program, because he believes 3-year-old children are too young to be away from home. The council would like him to reconsider.

Head Start is a pre-school program that teaches children basic language, motor and social skills. The county provides medical and dental examinations for the children, and parents are asked to attend monthly meetings and seminars on child development and nutrition.

Proponents of the program told the council that the sooner children from lower-income familes - the families the program is designed for - are included in the Head Start program the better for the children.

"When my first child went to Head Start," said Carmen Aguilera, "she didn't speak English. She learned English there. Most of the time we spoke Spanish at home." The social service workers connected with the program then directed Aguilera to English classes, where she learned most of the English she now knows.

"Many 3-year-olds are the last children in the family and they need sociability with other 3-year-olds," said Charles Wiles Jr., director of the Montgomery County Head Start program. "If we don't get them young we have to make up for things they didn't have. When the 3-year-old has a language problem, by the time he gets to school it's a speech condition and he needs a speech program. Also many of the families can only be concerned with how they've going to get food and clothing. They don't have time to give the child all the needs. We can give the child give those learning experiences he may be missing."

If Gleason approves the county application for the grant money, the council will then have to hold a public hearing and approve and the appropriation. The money could fund Head Start for about 60 three-year-olds, only a fraction of the 425 who are probably eligible under income guidelines, according to Wiles.

A family of four cannot make more than $6,200 a year under guidelines the federal government has set for the program. Head Start centers for 3-year-olds would be set up in four elementary schools - Takoma Park, Rock Creek Palisades, West Rockville, and Gaithersburg. All are near substantial lower-income populations, according to Wiles.

Criteria for joining the program would be based on living in the areas around the schools, low incomes and the severity of family problems in the home, said Wiles.