'94 Camry Vienta Overheats When Idling

[Djcocker]

I have a 1994 V6 Camry Vienta that overheats on occasion. This will only occur when the car has been idling for a considerable period, maybe 20+ minutes (as in heavy small city traffic), and is particularly likely on warm to hot days (25 degrees+). In addition there is considerable coolant loss through the overflow reservoir much of the time. I have received some advice that this is likely to be caused by a faulty radiator thermostat but I am seeking confirmation on the likelihood of this issue before embarking on a costly repair. Also any advice on the best place to source a replacement part would be much appreciated.

[The Don]

Replace the thermostat if it still overheats replace the radiator good luck.

[Hiro]

Check that your thermofans are turning on. If you're spending a lot of time stopped and idling then there is no airflow over the radiator apart from what the thermofans can pull/push through - this is why cars overheat at slow speeds in traffic and not blasting along the freeway at 110.

When you say "coolant loss", are you continually having to add coolant or does the level just change suddenly between when the car is hot and cold? When the coolant heaps up it expands into the overflow bottle, filling it up. As the car cools it draws this overflow coolant back into the radiator, causing the level to go down.

If you're continually having to top up the radiator and overflow bottle then you could have blown a headgasket, unless you are overheating it so much that the coolant is literally boiling and evaporating in the overflow bottle (possible, but it'd have to be pretty serious to be doing it in large volumes)

[Djcocker]

So a small amount of research has lead me to suspect that the problem is likely caused by the fan impeller motor. The fan on the back of the radiator spins but has almost no power behind it. It can be stopped and held in place with a finger. The radiator was replaced in the last two years. I had intended to replace the thermostat but it turned out to be somewhat inaccessible and a bigger job than first thought. Is there any way to test the function of the thermostat without removing it from the motor? Is the fan supposed to be spinning faster or with more power than that?
At times I have noticed the coolant bubbling into and then out of the overflow container as steam. The coolant loss is not large on any particular occasion, something in the range of a centimetre or two below the top of the radiator every 2-3 weeks. The engine has been pressure tested recently so it is unlikely to be a cracked head gasket.

Any ideas would be appreciated. Thanks guys.