He filled the bucket and returned, opened the radiator cap.

She reached for a grease cloth lying over the radiator cap.

He took a radiator cap from his jacket pocket, as illustration.

I yelled, dripping some water over the radiator cap, "Could you hold it there for a minute?"

"Not sure yet," I said, reaching for the radiator cap with the towel, but the cop spoke quickly to stop me.

The radiator cap acts as a release valve set to open at the maximum pressure point.

Wait at least 30 minutes before opening the radiator cap.

Learn more about how a radiator cap works from this article.

I thought of that when I saw your radiator cap.

Feet on the bumper, he had caught the radiator cap with his free hand.