When starting the engine after sitting for several hours, a knocking sound may be heard for several seconds. This is a common issue with the 2006-2010 Mercedes Benz ML350. There are three common problems that can cause this sound to occur:

-Oil pressure building too slowly, allowing for movement between the crankshaft and crankshaft bearings

-Stretch or wear of timing chain and components

-Balance shaft (counter rotating shaft) gear wear

The remediation for these problems can be crankshaft bearing replacement with correct size, replacement of timing components, or balance shaft replacement.