Editing Ford CVH engine (section)

==Common problems==
===Noise, vibration, harshness===
Throughout its 20-year production life, the CVH had a reputation for excessive [[noise, vibration, and harshness]] (NVH). [[Jeremy Clarkson]] said of the CVH-powered Escort that "''it was powered by engines so rough, even [[Moulinex]] wouldn't use them''".<ref name="gomog-hist"/> This harshness is mostly due to the cylinder head and valvetrain design.{{citation needed|date=December 2024}} At {{cvt|220|lb|abbr=on}} at full lift, the valve springs in the CVH are considerably stiffer than is typical in other engines. The stiff springs are needed to overcome the weight of the rocker arms and hydraulic self-adjusting tappets used and thereby prevent valve float, which they do up to around 6700 rpm. The stiff valve springs add more friction and pressure to the already high-friction "flat tappet" design.

===Sludge===
The camshaft is oiled by small holes in the cylinder head casting next to the lifter bores. These holes are prone to blocking up with [[oil sludge]] if the engine is not serviced regularly, starving the camshaft of oil. The CVH is known for producing excessive sludge if the service schedule is ignored or if poor quality oil is used. The cause is the design of the crankcase ventilation circuit, which Ford revised several times over the engine's lifetime but never completely cured. Due to this, camshaft and tappet wear problems are common. A worn camshaft can cause heavy clattering and ticking from the engine's top end, especially at high engine speeds.<ref name="gomog-hist"/>

===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.