what would cause a dull boing noise after car engine is turned off. on 1999 Buick Park Avenue

occurs in 2 seconds intervals for about 5 minutes or so after the car has been driven maybe 20 minutes.So heat of the engine factors into this happening. shorter periods of driving does not cause the noise to occur. This happens after the car engine is turned off.

by in Thiensville, WI on March 29, 2013
3 answers 1 comment
ANSWER by on March 29, 2013
your engine is decompressing(oil draining into pan). louder in some vehicles. rec. treatment with oil stabilizer on next oil change. this will recondition seals, and cylinders.
COMMENT by on March 30, 2013
Thank you for your response will give your rec a try.
ANSWER by on March 30, 2013
Most likely thermostat sticking then rapidly opening causing noise have cooling system checked!
ANSWER by on March 30, 2013
Have you opened the hood and checked coolant level? BOTH when cold (before first start of the day , and after it's been warmed up as you describe? OOOOOOOOOOOOOOOORRRRRRRRRRRRRR.........another wild guess....but I think wetry is most likely correct.......is that the exhaust may be clogged and overheating and you may be hearing the metal 'pinging' as it cools down.