We use very special tools for this. Snap-on sells a 13mm socket made to a 1/4" shank on a 3/8" drive for the pump bolts. We use the hazet allen socket set with wobble extentions to get out those stubborn allens.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS