While you're at it, check the battery tray. I haven't had a car yet where the battery tray didn't corrode (except for plastic trays). Some even disintegrated to nothing from the battery acid.
I always sandblast the trays to remove corrosion and coat with a rubberized coating (same as the dip coat they sell for tool handles) to prevent further rot.
95 E320 Cabriolet, 131K