That hissing sound wasn’t his car’s radiator.

A Queens man found this 2½-foot-long snake hiding in the engine of his Audi A6 yesterday morning.

“It started hissing, and its head came up,” said Rajesh Sooklal, 34, of South Ozone Park.

Cops removed the reptile, a corn snake.

“Members of this species are not venomous, [are] common throughout the Southeast, and kept as pets here in New York,” said Peter Ducey, a herpetology expert at SUNY Cortland.

Sooklal said his Audi had just been transported by truck from Florida.