94 Toyota Camry is Overheating

My 94 Toyota Camry V6 LE is overheating; I've replaced the radiator, the radiator cap, the water pump, the timing belt, and the over flow tank. Still, after about 35-40 minutes of driving, the noise the car usually makes when I hit the gas is MUCH louder than normal and this precipitates the gauge going above the halfway point. I got the water pump done today and after about 40 minutes of test driving the car, it made that noise again, and after I turned the car off the over flow tank was boiling and a small amount of water had come out of the top of it. The first time the car overheated I didn't notice the gauge was above halfway until it was all the way on 'H' and I literally couldn't drive it anymore. I'm worried that doing that did something that permanently damaged the car.

try new Thermostat

You may have killed the head gasket. Look for smoke from the tail pipe, or milkshake in the oil.

Do the coolant fans work proper? , check the fuse + relay.

The fan is running properly, a few people have said that it might be the head gasket, though the thermostat also has not been replaced. What's the likelihood that, considering the car's symptoms, that it is the thermostat? I'd rather have to replace that than the head gasket

If the thermostat was defective and sticking in the closed position, the car would overheat in just a few minutes; not 35-40 minutes.

Has a professional tech been doing all these repairs? Has the tech performed any tests to check for a bad headgasket? Assuming that it's not a bad headgasket and taking in to account everything that has already been done to this car, it may be that the entire cooling system is clogged. Has anyone suggested a backflush of the cooling system to get most of the crud out of it? How many miles are on this car?

Mike

Guess he fixed it?

Another possibility is that the valve that controls the hydraulic fluid that turns the fans, it's relay, or the coolant temperature switch has failed, most likely the latter. it is located at the bottom of the radiator near the center. When it fails, the circuit is stuck closed keeping the fans from running. Unplugging it will open the circuit and should turn them on. If this works, the switch is bad.

The V6 cooing fans aren't electric, they're hydraulic and the fluid is power steering fluid that comes from the PS pump. There is a control valve that regulates the flow to run the fans when it gets too hot. The temperature switch controls when the valve opens and closes and is a normally closed switch below operating temp.

Hope this helps!