So my 2012 Prius started to do the rattle upon ice start and got a code for a misfire in cylinder 1. I changed the plugs (cylinder 1 plug was fouled up the other 3 were good) changed the ignition coils. Car runs much better and typically on a normal day ice starts great and runs great until the car gets warm and it goes into ev mode then I accelerate at the ice kicks in and starts rattling untill it equalizes. I have also noticed it's drinking up coolant like crazy I noticed it was low filled it up to full and it's down past low after like 80 miles of driving. I also did a combustion gas test and it came back negative and a compression test just getting it to crank over without the fuel injectors connected. I will attach the compression test results. I checked the oil via the dipstick and didn't see a milkshake but maybe I need to drain it to see if the coolant is getting in it? I am 99% sure it's a head gasket leak but would like to know if there is anything anyone can recommend to check that could cause coolant to disappear without any visual leak and the engine to run rough either when it's warm or when the weather is hot and coolant becomes pressurized. The fuel injectors intake manifold and EGR were not cleaned yet and I am unsure of when they were last cleaned. I plan to clean everything if I am to replace the head gasket but I don't see how they would affect the coolant disappearance.
Head gasket. Save time and money and just replace the head gasket. Check the valve for leakage while the head is off. The longer you wait, the risk of bending a rod, and/or it going through the block...