I am a newbie to the world of the Prius. Recently bought a 2012, 1 owner that had great maintenance. I was doing normal driving and I got the triangle of death, check hybrid operation. Took it to a service shop and the code was 361B, coolant pump failure. It also has the knocking engine at start up. Is this code indicative of a blown head gasket?
With the startup knock and a failed water pump, it likely is a blown head gasket. It can only be determined by further testing. Compression test, leak down test, or combustion leakage test. Most parts stores have a combustion leakage tester that you can rent. It’s a clear tube with a rubber cone on it. Pour a special fluid in it, cap it off, and place it on the reservoir in place of the coolant cap. Draw vacuum on it with a hand pump while the engine is running. Color change indicates hydrocarbons in the coolant.
With the 3rd gens, it’s pretty much necessity to clean the complete EGR system and intake manifold, at least 100k back. Sadly Toyota is not alerting owners to this. More info: Bad Flywheel | PriusChat
Or, at least, check the intake manifold and clean its EGR passages as necessary, which isn't much more than a 20 minute job, somewhere around 100k-ish, combined with asking the car how well EGR is flowing overall, and scheduling any more-invasive EGR work (which is a great deal more labor) accordingly. The manifold check is worth doing irrespective of the car's flow-test report, because (a) there are four separate passages there, such that clogging can result in different EGR flow to the four cylinders but without the car's overall flow test detecting it, and (b) it is very minor labor to do. We really don't yet know how important the much more labor intensive job is at what mileage, because we still have way too few reports on that PriusChat EGR blockage data thread. My 2010 at 154,000 miles had good flow test numbers and light EGR pipe deposits about the thickness of paper. Some other cars seem to have much worse clogging. We don't know why, or how common it is (there are a lot of Prii on the road). It would be helpful if more people contributed their results on the blockage data thread. What would be especially helpful would be both before and after flow numbers contributed by people who do decide to do the full cleaning operation, along with photos of what they found before cleaning. That would start to teach us the correspondence between flow numbers and actual conditions found on cleaning. Too many people post about their grueling hours of EGR cleaning labor, and when asked "say, could you add your before and after flow numbers to the thread", turn out not to have thought to get 'before' numbers when they started, and then it's too late.
A lot of people have good experience with sealers. I did not have one. I used the Blue Devil Pour and Go. It was a 90 day repair, then the head gasket failed(again/anyway), maybe in a different spot. Maybe see about a borescope inspection of the cylinder to determine how large the leak is. If you are getting just a few drops into one cylinder, maybe a sealer is a good choice. Multiple cylinders, or a steady stream, it may be too late for a sealer.
I have seen mechanics use K&W with maybe three month results. See my other post today for required steps and cautions.
