Originally Posted by
KnappAttack
C3 was out first and went thru teething problems just like EC is now. This C3 is the latest of the C3 designs and has proven bulletproof. Also, its steel and will last forever, unlike like the EC which is alum. and wears right out.
I'm not sure if C3 is still in business or not, I don't think they are but I'm not certain.
Not quite true EC makes or made St.Stl and Aluminum pulleys. Nothing lasts forever, the OEM ones will fail at some point and I do not mean the bearing. The springs are subject to flexing and so must fail one day. Some of the new pulleys have split in half as well.
There are records of the OEM ones failing, maybe on the Merc forums.
The weakness of the EC pulley is the so called spring, the last post on a EC spring failure mentioned that no replacement was forthcoming but a new one could be purchased.
If you have fitted one of the new pulleys I hope you have kept your original OEM pulley as you will need it.