01/04/2026
You’re looking at a Prius 4 cylinder engine from a top down view and the head is removed. The four round components are the superior aspect or dome of the 4 pistons. They are housed in individual cylinders.
I left the head gasket on the engine block deck, the flat surface on top of the engine that the head sits on and mates. The head gasket failed at cylinder #2 and allowing coolant into the combustion chamber. Cylinder #2 has the polished dome. The carbon was cleaned off of the dome from the coolant dissolving it and heat during combustion. This hg failure was not caught early. Fortunately, there is no bent rod.
This client spent over $3500 for parts and labor and three visits to the dealership prior to being told they needed a donor engine because this particular dealership didn’t replace head gaskets. They told the client that the engine was not good. Their tech followed the Toyota/Lexus TechStream algorithm and followed the codes. We too have a software license with Toyota and have access to the same data. There is a reason we do visual diagnostics prior to connecting a code scanner. The software was written to sell parts and services, the most profitable division of any auto dealership. If the tech looked down the spark plug hole he would have saved the client three trips to the dealership with unresolved issues and over $3500 of parts and labor.
A quick peel inside a hole tells a story.
To help steer the Prius community the right direction we don’t charge for diagnostics.
