This fall i have noticed when i first start my car in the morning (its sits outside) it makes a loud rattling/knocking sound. You can hear it very well in the interior, and when i pop the hood and listen it sound like it is coming from the front exhaust manifold area, it goes away after the car has warmed up. any ideas? by the way the car has 97,000 miles on it.

Thanks

 

Same here. I've heard this noise described as piston slap. Anybody else having this?

 

Cam you record the sound and post the clip?