Question: Should I fix a blown head gasket or replace the engine?

 

I recently bought a 2004 Toyota RAV4 4WD from a private party with 207,000 miles, automatic transmission, no OBD errors, relatively new water pump, 2AZ-FE engine. A rookie mistake; I did not have a mechanic inspect the car before buying it. I intend to own the car for another 5+ years and use it to make 10-15 weekend trips to the mountains (400 mile roundtrip) a year, as well as 1-2 small trips in the city a week (say, 9000 miles/year).

 

My mechanic has diagnosed a blown head gasket and says with a lower mileage vehicle, he'd typically just replace the gasket, but because it is a higher-mileage engine, recommends replacing the engine with a lower ~100k mileage one. It will cost more than double to replace the engine.

 

Context: After purchasing the car, I drove it for about 20 miles and saw the engine temp was reaching red on the highway. I realized the coolant was low and added 1 gallon, then topped and burped the system. Over the next 2 weeks, I took it on a few 15 mile trips and then a 100 mile drive and at this time started smelling coolant blown into the cabin. After the 100 mile drive, I checked under the hood and started saw a good deal of dried coolant around the front of the engine near and below the exhaust manifold, dripping and evaporating down along the main exhaust pipe. About a quart of coolant was lost over 100 miles and the engine temp stayed normal during this time. The car drives powerfully and idles quietly.

 

Before taking the car to the mechanic, I troubleshooted other parts of the coolant system: radiator, fans, radiator cap, hoses, and did an engine block test, which stayed blue. No white smoke from exhaust, no noticeable loss of power, no milky motor oil or froth, no oil in the coolant, no leaking from the back of the engine. So from what I can tell, the gasket issue is leaking coolant from the engine jacket to the outside front of the engine, not from the jacket to the combustion chambers/motor/cylinders/etc. There also doesn't seem to be a sign of stripped back of engine bolts that are common for this model of engine.