2012 Plugin Possible Head Gasket Failure at 210k mi While in Canada

Sorry in advance for the long post, I just wanted to be thorough to get the best advice The car has 211k miles, oil changed at 10k miles until 150k miles where ever since I’ve done it every 8k miles. Coolant crust on water hose since about 120k miles. This never got worse and the car never leaked coolant. Ive asked multiple dealers when the service interval is and they've all said not to replace until failure. Ive had mild knocking on cold startup around beginning around 150k about once or twice maybe every 4 to 6 months. Spark plugs are due for service, EGR and intake have never been cleaned. I asked multiple dealers to do the EGR TSB at 140k but they refused since there was no code and they couldn’t replicate the issue. I should’ve done the EGR myself but didn’t have a place to work on the car and money was very tight at that particular time.

About 1 week ago the car had very significant knock on cold startup. So much so that the CEL appeared. I have a basic obd2 reader but there were no codes when I tried to read it despite the CEL still being on. The CEL stayed on for 2 more days (during which time there was only a moment of startup knock on 1 day) but went away while driving.

2 days later I cold start the car, no knocking, drove about 15 miles at highway speed, stopped somewhere for about 10 minutes, no knock on startup as I left, drove another 2 miles, stopped somewhere else for about 15 minutes, started the car with no knocking, but as I left the parking lot there was moderate knocking and a little bit of hesitation from the car. No CEL, and the car drove just fine on highways speeds again for 15 miles. At this point I was worried and started to investigate the car. I found the oil looks fine, no crud on the oil cap, no difference in the appearance of the coolant system, but for the first time ever the coolant was just at the low mark and not at full.

Same thing happened again the next day where it started and drove fine, but when I went to leave somewhere id been for just a short time, the car had mild knock, but then drove fine.

The next day I drove the car about 2 miles with no issues. I checked the next morning and the coolant level had dropped about 1 inch below the low mark. Despite being cold, the coolant cap let off a lot of pressure when I removed it. There was no weird smell, no crud on the engine oil cap, and the oil looks fine. Im concerned that the head gasket may be done, and I haven’t driven it since, nor do I plan to until this is resolved in some kind of way.

This morning I checked the coolant and there seems to be slightly more (half inch to an inch) in the reservoir than yesterday? Could just be a parallax issues, I don’t know.

At this point I plan on doing the spark plugs and cleaning the EGR cooler myself as well as possibly the intake cleaning, and hoping that this can save the head gasket.

This has happened at a very bad time. Currently owe a few thousand more than the car is worth. I’m a US citizen currently staying with my wife in Canada and going back to the states really isn’t an option for the next 3 to 6 months while we sort out her US citizenship otherwise id likely just eat the negative equity and trade in the car for a Gen 4 Prius which I can’t do in Canada. The car is a plugin and I have a charger so I hope that I can do an interim repair and just use the electric power for groceries and such within a few mile radius. Most of the driving ill need to do in Canada will be within my plug-in range. The main concern is the 1900 mile journey back to the states

I don’t know of any reliable independent / Toyota mechanics to either do a head gasket job or an engine swap though if anyone in Ottawa Ontario can refer me to someone I may go that route provided it can be done for a reasonable price (something under $2k USD.)

My questions are:

1. Is it possible that new spark plugs, cleaning the EGR cooler, and intake would alleviate the pressure in the engine to the point where the car could run for the next 6 months?
2. Is it advisable for me to do the repairs in question 1 and then either tighten the head bolts to provide more pressure on the gasket and/or use something like Bar’s Head Gasket repair hoping the car can make it another 6-12 months? I’d never think to do either thing in normal times but here we are.
3. Is it possible that the misfire is just old spark plugs and the leak is unrelated? This seems like wishful thinking but if so, what are some common places for me to check coolant leakage?

Thanks for you help!

 

Thanks for your response! I definitely have the time, and am reasonably confident in my ability, particularly with all the write ups here and the various videos on Youtube. I do seem to be losing a bit of coolant, maybe a half inch in the reservoir per drive. Is that an indicator that the head is completely failed or is it possible that a full egr cleanse would stop that small coolant loss?