Description Reviews If you're replacing the water pump on your gen 1 MINI Cooper S, you should also replace the small o-ring (item #2 in the photo) that lives behind the neck (item #3 in the photo) that the water pump goes into on the block. It's a small price to pay to do the job right the first time. This is a high quality aftermarket item that is good as the OEM part, but at a lower cost! 1 Review 5 Water pump o-ring Posted by Joshua Owen on 23rd Feb 2022 This o-ring is as the diagram says, works for the water pump itself and the flange that meets the engine block. Works as intended and does not leak coolant.