PINGS

Worrisome motor noises

• Bullets-hitting-metal sounds

• Dreaded engine sounds

• Engine knocks

• Engine noise

• Engine sounds

• Knocking engine sounds

• Knocks

• Metallic impact sounds

• Signs of engine trouble

• Sonar echoes

• Sonar pulses

• Sonar sounds

• Submarine sounds

• Unwelcome engine sounds

• Worrisome engine sounds