2009 Scion tC 189k miles. Automatic.

About 3 weeks ago my engine started overheating while driving. I took it to 3 mechanics and they all told me different and similar things on what it could be but none of them could pin point exactly what it was.

These are all the possible parts that could be wrong according to them:

• radiator cap

• thermostat gasket

• coolant temperature sensor

• water pump

• blown head gasket

I’ve already done and replaced everything with the help of my dad except for the last 2 parts and it’s still overheating. The only thing the mechanics could confirm is that there’s no leaks and my coolant pressure is right so it has to be a failing part.

What are your thoughts? Is there any way I can know for sure if it’s the pump or a blown head gasket? Seems like the mechanics couldn’t.

If it’s the water pump, it’d be around $500 (parts & labor). That’s the cheapest I found in the Bay Area from 2 different mechanics with good reviews on Yelp. If it’s the head gasket, I’m looking at about $3500-4000 and 2 weeks of work.