Review on ACDelco 252 994 Professional Water Pump by Mark Sutovsky

The product is declared as an OEM product and I hope so. I bought this block because when buying a pre-assembled block there will be no question of pump assembly. The installation of the pump on the housing was successful. However, when it came time to reinstall the thermostat bypass tube and o-rings, that all changed. The problem was the top o-ring, I damaged the o-ring during installation and bought another "OEM" o-ring which also damaged it. Eventually I went to the GM dealership and bought both O-rings. The top o-ring was different, the diameter of the material itself was smaller. Installation went much better, seat felt under the pipe, no leaks, no damage. I've completely lost confidence in the entire kit, not just the o-ring. The reason for two ratings instead of units is that GM may have updated the o-ring specs. Much luck