I was following one of the guys in our truck club home one day and saw something fly out from under his truck (1952 Chevy). He slowed down and stopped as soon as he could get off the road. He said it made a loud bang under the hood and started vibrating badly. He looked under the hood and the oil filler cap was off. He thought somehow he built up pressure and blew it off. I went back down the road to see what fell off. It was one fan blade that had broken off. Then we could see that the fan blade came off bounced on the underside of the hood and knocked the filler cap off in the process. A 3-sided blade makes a bad vibration!
Good Luck, Buddy in AK
