I was curious to see if there was water pump rebuild kits on ebay.
ebay search = (the make year and model were typed in to the automotive search section)Water Pump rebuild kit, comes with no seal spring
MERCEDES W111 220 SE SEDAN COUPE CABRIOLET WATER PUMP REBUILD KIT 121 200 29 01 At $75 + about $6 shipping
Mercedes 190sl Ponton 170s 220s OM636 water pump kit$60 free ship $60 free shipping
You can get a new Gates water pump for less.