Manor Care Inc. sold three nursing homes and paid off a $167 million loan during its third quarter, giving the company a 270 percent gain in profits, Chairman Stewart Bainum said yesterday.

Earnings for the third quarter ended Feb. 28 increased to $4.5 million (38 cents a share) from $1.2 million (12 cents) last year. The loan, taken out to acquire Cenco Inc. in November 1981, was paid in full, thereby reducing company interest expenses.

Revenues decreased in that period from $83.1 million in 1982 to $78.3 million this year, largely because the company has 13 fewer nursing homes and divested itself of its industrial businesses, Bainum said.

For the year to date, the Silver Spring lodging firm earned $12.2 million ($1.14), compared with $7.1 million (70 cents) last year. Revenues increased to $261.4 million from $171.1 million in 1982.

Manor Care runs 101 nursing facilities, and its Quality Inns subsidiary has 452 hotels and resorts.

General Defense Corp., a Hunt Valley, Md., firm that makes tank ammunition, targets and jet engine parts, said yesterday that its profits jumped 29 percent over the fiscal year 1983 to a record $9.5 million ($1.19).

In the previous year, the company earned $7.3 million (93 cents). Revenues increased to $78 million from $70.7 million.

For the fourth quarter ended Jan. 31, the company had profits of $2.8 million (35 cents), compared with $1.8 million (23 cents) the year before. Sales increased to $24 million from $17.7 million.