The government is investigating General Motors' recall of 2 million 1978 vehicles to determine whether a wheel bearing problem is being corrected properly and whether other models should be included.

The recall, announced by GM last month, covers the entire 1978 production of Buick Century and Regal, Chevrolet Malibu and Monte Carlo, Oldsmobile Cutlass and Pontiac Lemans and Grand Prix intermediate-sized cars, and GMC Caballero and Chevrolet El Camino light trucks.

GM recalled the cars after pressure from both the National Highway Traffic Safety Administration and Canadian safety officials.

The company said temperatures in the front outer wheel bearing may reduce lubrication below the necessary level.

The automaker's remedy includes installation of new outer wheel bearings and new grease retainer caps, new bearing lubricant and coating the spindle with additional lubrication.

The traffic safety agency said it wants to learn if this corrective action is adequate. It also wants to examine any reports of front wheel bearing failures in other 1978 GM model autos, including compact, sub-compact and full-sized vehicles.

The agency said it has received about 700 reports of front wheel bearing failures, including about 100 in 1978 GM cars not covered by the recall. Seventeen accidents have resluted from the problem in this country, it said.

Although none of the U.S. accidents caused deaths, Canadian officials said one person was killed last October when a Buick Regal went out of control and rolled over after a wheel bearing failure.

Most of the failures have occurred before the car has traveled 24,000 miles, well below the 30,000-mile maintenance check on front wheel bearings recommended by GM, the safety agency said.

The agency said symptons of the trouble are a grinding noise or frontend vibration, or both. It asked anyone experiencing the problem to write the National Highway Traffic Administration, 400 7th St. SW, Washington, D.C. 20590, or to call the Auto Safety toll-free hotline, 800-424-9393