After a day of loud complaints over salaries from county government workers that included a police slowdown, the Montogomery County Council approved a $512 million budget yesterday that may require a 1-cent increase in the property tax rate.

After much wrangling, the Council finallty agreed on raises of 4.2 per cent for the 7,000 county government and 13,000 school employees - a slight increase over the raises decided on last Friday.

Whether or not the county's property tax rate of $3.91 per $100 of assessed valuation will have to be raised by a penny won't be known for another month, when revenue from the income tax can be gauged.

But property tax bills will go up anyway, because the value of houses in the county, and therefore the assesments on them, have been increasing.

The Council's action capped five days of controversy marked by picketing by hundreds of county employees and demonstrations at the County Office Building in Rockville.

What particularly angered the employees was the Council's decision last week to give them cost-of-living raises of 4 per cent and to make them contribute more to their health insurance tribute more to their health insurance - up to 29 per cent of its cost.

Yesterday the council decided by a 4-to-3 vote, to require county government employees to pay only the 11 per cent of the cost of their health insurance previously agreed to under a payment schedule effective in July.

Higher insurance payments by the county government workers would have brought their payments into line with those made by teachers and other school system employees.

The question of equalizing contributions to the health insurance program made by county government and shcool employees was postponed until next year, and some observers said it could become an issue in the 1978 Council election campaign.

In March, County Executive James P. Gleason recommended a $509 million budget for county government and school operations that would provide 4 per cent raises and require no incrase in the property tax rate.

Although the Council finally agreed to 4.2 per cent raises, the county's 13,000 school employees had negotiated a contract with the county school board calling for 6 per cent raises.

The school board may consider honoring that contract by taking money away from some school programs or reducing the number of school employees in order to fund the full 6 per cent raises.

Cuts in the school budget already have resulted in elimination of such things as interscholastic sports in junior high schools and 105 summer teaching positions.

One result of this year's budget deliberations may be increased pressure for county employees to unionize.

"I don't think there's any doubt this will give a big boost to unionization," County Executive Gleason said. The Council's actions "make employees feel the only way they'll be listened to is if they're organized," he said.

School system wmployees now are the only county workers who unionized. Recently the Council approved legislation allowing the formation of employee groups to meet with the county government over salary and other employment issues.

State legislation that would have al- lowed unionization of county employees failed in the General Assembly this year but is expected to be introduced again.

Council President John Menke said he hopes the Council's actions will provide a "boost in the other direction, following the intent of the meet-and-confer legislatin," rather than give impetus to unionization.

Menke disputed some observers' contention that the Council had backed down on its earlier budget decisions in the face of county employee pressure.

"The (county) employees registered their dissatisfaction with the process of our increasing their (health) insurance costs," Menke said. "We realize they were right in saying the process was wrong."

Memke said he still believes the disparity in insurance costs for the various county employees must be corrected, but that the Council should consult with all employee groups before taking such an action.

James Mills, president of the Montgomery County Government Employees Organization, said he was "relieved" at the final Council vote. "The employees didn't get anything elaborate, but we didn't lose anything," Mill said.

"We have to figure we scored a victory."

Len Simpson, president of the Fraternal Order of Police, sais the County employees' presence in a packed chamber was responsible for the final vote. "We were there to keep a watchful eye on the Council," Simpson said.

Simpson also claimed that the "job review" instituted by many police officers yesterday was instrumental in influencing the Council.