I've received a variety of opinions regarding what may actually be wrong with my car. Here is the story so far...
~96k miles: Bought 2008 Toyota Highlander Hybrid from dealership. One owner, full service history, nothing major replaced save timing belt at 90k.
~96k miles: Serviced by mechanic friend, changed oil checked fluids etc.
101,500 miles: On way home from trip, heater stops working. Check nothing (brilliant I know).
101,750 miles: Car overheats, take to mechanic friend shop. Oil level is fine, coolant super low (like out). CEL on, random misfire in cyl 4 and 6. Mechanic friend thinks needs head gasket, doesn’t have time to do the repair for us. No external coolant leak. Fills with coolant, runs ok. Coolant system holds 10 lbs pressure but drops when pressurized to 15.
101,780 miles: Take car to independent auto shop, lost some coolant on the way (3 inches or so of reservoir). They find nothing wrong.
- 101,800 miles: Car used almost entire reservoir of coolant, back to independent shop. More inspection, CEL back on with random misfire in 4/6 again. Now they think it may need head gasket but they are not sure.
- 101,800 miles: Took to new shop for more inspection. Car is now super low on oil, like 2 quarts. Tech put coolant system under pressure and ran car, which caused misfiring immediately. Removed spark plugs 2, 4 and 6, oil ash on 2 and 4 is wet with coolant. No external coolant or oil leak. Considering loss of oil and coolant, they recommend new engine. Want $$$$$$ for install. Filled with coolant and oil.
- 101,850 miles: Found new shop with good reviews and better price on engine install. Drove car to them, did not lose much coolant on the way, < 0.5 inches of reservoir lost. Oil level seems fine. Car running ok, no CEL on yet. Told story to new mechanic, he is not convinced it needs an engine. Recommends bottle of Subaru coolant conditioner and driving it more to observe behavior.
- 101,900 miles: Idle is rough, but running ok. Coolant loss is now very slow. CEL back on, random misfire in 4/6.
- 101,920 miles: CEL on again, random misfire in 4/6. Coolant now down 0.5-1 inch since last filled (101,800). Oil level is fine.
Spark plugs 2, 4, 6 (not exactly sure on the order):
At this point I have purchased a used engine, which is sitting in will call at the scrap yard. I have about 25 more days to decide what to do or they will charge me 20% restocking fee.
My questions are:
Should I go ahead with the engine install at this point, or should I have more tests done?
If I am going ahead with the engine, I have 3 different installers to choose from:
The shop who recommended the Subaru
snake oilcoolant conditioner. They have good reviews on yelp and a good price on the install (I gathered quotes from 4-5 reputable local shops).
Friend of a friend will install for same price as latest shop. Retired Toyota mechanic, working from his home, nearby.
Friend of a friend will install for ~50% the price of the latest shop. Younger less experienced mechanic, 50 miles away.
Any input or advice is appreciated.