DETROIT — General Motors Co. has decided to replace several key engine parts to stop oil leaks that have caused more than 1,300 fires and four recalls of older cars.

But the parts aren’t available yet, and GM is still recommending that the cars be parked outside until they can be repaired.

The company says in a notice to dealers that it will replace the front valve-cover and gasket with improved parts under two recalls announced earlier this year. The recalls cover about 1.4 million cars with 3.8-liter V6 engines from the 1997 through 2004 model years. Models include the Buick Regal, Oldsmobile Intrigue, Pontiac Grand Prix and the Chevrolet Impala, Lumina and Monte Carlo.

Oil can seep through valve cover gaskets designed to keep it inside the engine. Under heavy braking, oil can drip onto the hot exhaust manifold and catch fire. Previous repairs on most of the cars only included moving flammable plastic parts away from the oil, but did not stop the leaks.

GM said in documents that 1,345 cars have caught fire after being repaired under earlier recalls, which started in 2008 and 2009. The company reports 19 minor injuries and at least 17 structure fires because of the problem. In one North Carolina case, flames spread from a Pontiac and damaged two houses.