Editing Ford CVH engine (section)

===Valve seat failure===
A common problem with later CVHs is their tendency to drop a valve seat,<ref name="Valve seat problems"/> which happens most often in VIN number P engines. This can occur with no warning, even if the engine has been well maintained. In most cases, a seat drops on the number 4 cylinder, with the next most common being the number 2 cylinder. With the factory valve seats, the typical life of the 2.0&nbsp;L SPI in a Focus is about {{cvt|100000|to|120000|mi|km|abbr=on}},<ref name="Valve seat life"/> but a failure can happen as early as {{cvt|70000|mi|km|abbr=on}}. When the valve seat drops out of the cylinder head, it falls into the cylinder and damages the cylinder wall, [[piston]], and [[cylinder head]]. In some cases, the valve seat is drawn from its cylinder through the [[intake manifold]] into another cylinder, where it causes damage.