The Spad 13 235 hp was good and reliable in the french forces.
The spad 13 220 hp was not very reliable, and the Spad 13 200 hp was absolutly unreliable unless maintained by a skilled mecanician.
It seems that the problems were vibrations generated by the engine which damaged or broke the cooling system (as reported by meeting minutes beetween the aircraft maker and the French forces representatives)
But archives are a little sketchy
Note that most french aces were either highly skilled mecanicians (such as Fonck) or worked with very good mecanicians (Guynemer ...).
This was often key to their success, but particularly with the Spad 13
Lot of French pilots kept their trusty Spad 7 180 cv until July 1918, such as for instance Pelissier (an ace with 8-12 kills, officially 8)