The cap snaps off with a screw driver under neath is an allen screw. The new pulley comes with a new cap. I just replaced my pulley just in time before it self destructed.

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Ricali

03 C240 4matic wagon
95 300E 234,000
7 prior 240;s 5 still going
81 300sd gone
65 230sl gone
49 Studebaker Champion
90BMW convert.167,000
60 Dodge D-100