Abstract: A split mechanical face seal having a rotating seal assembly comprising a rigid seal ring of split ring segments and a pair of attachable body ring segments holding the rotating seal ring segments together when the body ring segments are attached, a stationary seal ring assembly comprising a rigid seal ring of split ring segments and a pair of attachable housing segments holding the stationary seal ring segments together when the housing segments are attached, a single segment retainer ring having a split forming first and second opposing end faces, the retainer ring being made of a flexible material, the retainer ring being operatively engaged with the stationary seal ring segments and resilient members carried by the retainer ring and operatively engageable with axially facing abutments formed in the housing segments when the housing segments are attached such that the retainer ring exerts a biasing force against the stationary seal ring segments in a direction toward the rotating seal ring segments.