My mechanic performed a compression test and confirmed it was the head gasket. They performed a head gasket sealer which turned off the CEL for one day. The prius still knocks at start and will misfire while accelerating. I am looking to make this car last as long as possible in it's current state. I do not want to put anymore money into it. I will only be using it for my daily work commute of 26 miles. I have read that taking off both coolant caps and running high heat at start up will help with the drive. Is there anything else you can recommend?
Flush out the sealer and replace head gasket. Never mind; you don't want to spend any more on it. Just postmortem: What's the miles? EGR system ever cleaned?
324,000. Full EGR assembly was replaced 1 year ago. Spark plugs in March. New tires in December. Now you can see why I don't want to spend anymore money on it and want to make it last as long as possible in it's current condition for my daily 26 mile round trip work commute.
Run it until a piston rod breaks and puts a hole thru the block and leaves you stranded during your commute.
I have good sam roadside assistance. I also plan on trying to drive in EV mode as much as possible and when not in EV mode I plan on keeping the RPM low.
ev mode just makes the engine run more, but maybe at less harmful rpm's, idk. keep the a/c off if you can stand it.