This is a one family car driven exclusively in Southern California with perfect maintenance using 0-20 full synthetic oil and top grade oil filters. Never burned oil, always perfect in all respects for 120,000 miles. Only service, other than book maintenance, were for the electronic recalls. NO issues and best car we ever had... Then it began to miss fire upon overnight or approx 8 hrs. parking for about 20 seconds. This went on for about two weeks before I took it into a trusted Toyota dealer. Their computer showed a miss in cyl. #1 and darkened Toyota Red coolant. They took out #1 spark plug, which had only 1,000 miles on it after the 100,000 major tuneup, and scoped the cylinder wall which were badly scored. The plug also showed coolant damage. With that, the quote for a new engine block etc. was $8,000. It is obvious that this option was not acceptable. The final decision is to put in a JDM engine and drive it till it dies. As of now, the car has new tires, original 17" rims, new front brakes which were all done at the major tuneup. The leather interior 5 series car is otherwise in perfect condition. And here I thought Toyota's had long lasting engines. I'm totally PISSED.
That's terrible, but your experience is nowhere near normal. It's very common for 3rd gens to go 150-200k without a single minor or major issue using only regular maintenance. You could have gotten that rare lemon, it happens with all manufacturers. Some more than others of course. *cough* *cough* GM *cough*
You said red coolant? It’s supposed to have the pink. If your down in SoCal, I’d look up @Avi's Advanced Automotive and see what he says.
Have a look at the EGR system, starting with the pipe, @NutzAboutBolts video #16 here: Nutz About Bolts Prius Maintenance Videos | PriusChat This inspection will take about an hour, a fairly easy DIY. This won't really help you, but might give some proof as to why the head gasket failed.
The coolant was probably darkened from combustion gases due to a failed HG. The head gasket failure is fairly common on the 10-15's. Usually it does not happen until after 150K, but anyone in the six-figure mileage category should considered themselves warned.
