When i start my 136k miles 2010 Prius, it starts fine but i can hear a continuous low volume knocking. After working for about 20minutes switching between Hybrid and Combustion Engine a couple of times, it switches to combustion, increases the rpm and doesn't switch back to Hybrid. Coolant temperature would increase to 90-95 degree celsius and i see it boiling in the coolant tank. When i off the car, the combustion engine shakes heavily. Cylinder 3 and 4 misfire code come up sometimes. CONS: Car at 136000miles, Head gasket not yet changed. Changed EGR valve Changed Fuel injectors Cleaned egr cooler and intake manifold. PROS: I am not losing coolant. Checked cylinder valve via Borescope camera through spark plug hole and can see exhaust valves with heavy brownish build up. Engine cylinders has some burn/rust looking surface and like an oil in Cylinder 4. (see attached pictures) I want to know if this issue can be caused by a failed head gasket and if the cylinder build up is from same or something else.
If Your head gasket failed, bubbles in the coolant are from exhaust gasses in the coolant system. Borescope down the spark plug holes look at the tops of the cylinders. You might see a clean top on one which is a clear indication of a failed head gasket, maybe not since you are not losing coolant.
I also realize i do get p3020 error when this happen. Can a battery block 10 error cause such issue. I mean it seem this doesn't allow me accelerate properly after that error comes up, even after i clear it with Dr. Prius unless i shuts off and on.
IF you get bubble in the coolant tank, the engine in ruined. It rarely gets that far with the Prius. Loosing coolant, knocking, missfire codes, are huge warning signs of a failed head gasket.
Thing is, i am not losing coolant, i can open coolant tank when engine is working. I So i am thinking perhaps the battery issue makes the engine keep working when it should have switched back to hybrid or something.
No, I monitored via Carista app and it's <95 degree celsius, never gets to 100 which is when the symbol do show in dashboard. So i am trying to change the block 10 battery, in other to check if that might be the issue.
