Thursday, January 24th, 2013 AT 4:11 PM
After my 2007 corolla runs for avout 20 minutes, when the car is in motion, I hear a "pinging" noise. It is similar to the last kernals of popcorn popping in a pot or the noise you hear from under the hood when you turn a car off. The noise is not evident when the car is stopped. It does not really increase in intensity with an increase in speed. What can this be? Thanks.