The only time they're not rebuildable is if the piston or bore are pitted from corrosion. Rebuilding calipers is always much cheaper than replace.

All you need is new piston seals and dust boots. A pair of good hands, and some caliper assembly lube. A cheapo 12v tire pump is handy for pushing the pistons out.

Flush / change your brake fluid every 2 years like Mercedes recommends and the brake hydraulic components will last nearly forever.

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1998 E300 turbodiesel

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