Water pump removal made easy: M103
 

I used 1/4" drive Snap on flex head ratchet TH737 with a one piece 6 mm bit from AST tools, bit is strong and short. This was use to remove the top front bolt. All the other bolts were regular 13 mm.

I used a Snap on FLXM13 to remove all three other bolts which were 13 mm. The socket is the size of a 1/4" 13 mm socket as is the extension part except at the end where it is sized for a 3/8" drive ratchet.

If any of the other bolts were 6 mm hex head bolts then you could most likely use a 1/4" drive stubby hex universal, part number TUAM6E, made by Snap on.