>> C << Valve Spring Retainer Lock Installation
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
In the same manner as removal, use special tool valve spring compressor (MD998772) with special tool retainer holder attachment (MB992090) and special tool retainer holder C (MB992089) attached to compress the valve spring, and install the valve spring retainer lock.