Gas Engine Shakes at Startup

My car does a similar rattle once every so often, it’s done it maybe 3x in the past 2 years…the research I’ve done this is what i believe is happening…an engine rattle when starting your Prius v, especially in wet or humid weather, is a very common issue across third-generation Priuses. It is typically caused by condensation pooling in the intake manifold overnight or an early-stage head gasket leak leaking liquid into the cylinders. I don’t think it’s an early stage head gasket and never had any engine issues other than the egr. In 8/24 at 175k I changed all the coolant in my radiator and inverter, and the cvt fluid. I change my oil every 5-6k miles using mobile1 synthetic extended performance which is 20k miles oil. Now 7/26 I’m at 211k and still no head gasket issues. My car doesn't use any coolant and only uses maybe 1/3qt oil when it’s dirty and due for a change. I honestly believe it’s from the condensation pooling like it says online and the times it has done it was after heavy rains and it sat 1-3 days without driving it.

 

One small little detail that you did not list is that you replaced the engine at 165k miles. Why did you replace the engine?

In a new thread you created today you wrote: