A wing liner is the protective shield, sometimes referred to as a splash guard, usually made of plastic, that lines the wing, helping to protect it from rust, and functions to keep the engine compartment clean, preventing water, mud and other debris from the road entering the engine, which can cause big damage.
The wing liner stops the build up of dirt inside the wing, and also on door hinges, preventing water and other objects from gaining access, which helps to slow down rusting on these parts, and damage to the bodywork. It can also, in lots of cars, stop water reaching wiring and electrical components. The wing liner also acts in some way as a noise dampener, helping to fend off noise from the road as the car travels along.
The wing liner is locked into place with plastic rivets, clips or pins.
Damage can occur to the wing liner if it comes loose or is torn. This can cause the liner to drag on the road, hit the wheel when turning, and rub against the wheel. If the wing liner is damaged in any way, or it has come away from the car completely, it is advisable to get a replacement as soon as possible to avoid any possible damage, particularly water damage to the engine. It is not recommended to drive without the wing liner in place and in good, sound condition. If buying a new wing liner for the wing, it is important that you buy a wing liner so that it fits the correct front wing and the make and model of car perfectly.