Hi PriusChat I got my first long Engine Knock today and last about 25 sec. and the engine shaking. SoCal weather has been raining last 3days, but NO flood in my area. Outside weather Temp this morning about 50 F My Prius Spec Yr 2013, 119,920 miles. Daily commute 20-25 miles per day. Oil Change every 5000 miles Last EGR Valve and EGR Cooler clear @ 99,200 Oil Catch Can installed @ 98,500 and drain 2-3 teaspoons out on every oil changed. What should I do next to prevent further knock before i arrange to change the engine gasket.