What is the circular ridge for on a 2008 Prius water pump gasket and does the high part of ridge go towards the engine block? Also I’m confused as to wether to use RTV. There seem to be two schools of thought on this. Thanks.
You can only orient the gasket one way to fit with the coolant pump because the pump shape is not symmetrical. Note how the original coolant pump gasket is oriented as you remove it. If you use the correct Toyota gasket and coolant pump, and observe the correct torque spec when tightening the nuts/bolts, RTV is not required. My thread on that subject is here. How to replace engine coolant pump and thermostat | PriusChat
I replaced the water pump in 2011 with just the paper gasket and no sealant. Still no leak. However, I need to replace the water pump again since the weeping hole shows pink dry staff. I bought the Cardone water pump 10 years ago from rockauto and it had lifetime warranty. I hope they still honor it. I used the pump only 95000 miles.
