How Important Is The Thermostat?

[choppacity305]

ok guys as u know my 93 es 300 is still overheating i have replaced my radiator and with new hoses.Unfortunately, i still havent solved the problem there are no obvious leaks the water pump is ok and the fan is running at normal speeds.The only other thing that can possibly be wrong that they tell me is blown head gasket or i need a thermostat.But the thing is i never had a thermostat to begin with when i bought the car 2months ago now overheating problem starts.My question is the thermostat really that important too have? because thats the only thing i can think of besides the head gasket and god knows i hope thats not the problem.So please!!! help me with your expertise on a possible solution guys?

[Toysrme]

1) Yes, you need a thermostat. Especially on a 3vz-fe. They run cold , and you really don't want to over-cool them.

2) Make sure the new radiator has a radiator cap on it. More, and more often replacement radiators will be for the later 1mz-fe engine's which have no cap. That cuts the boiling temperature of the coolant tremendously. The 3vz runs naturally colder than it should - during even our mild southern winters, you'll never notice the problem. As soon as it warms up outside, you'll overheat very, very quickly.

3) Replace the cap on both the engine outlet, and the radiator. Specifications are: the engine outlet specification is 12.1-16.4psi. The radiator is 13.5-17.8psi.

4) Overheating is often to happen on any car when replacing any thermostat. It is very common to get a defective part, or the wrong part.

5) Check that the water pump is working OK.

When you say the fan operates normally. That means it speeds up when the air conditioning is turned on, or the engine is under use correct? Also, bridging E1, and OP1 in the diagnostic port makes the fan spin fast correct?

Yes, overheating can be caused by a cracked/warped block, cylinder head, or blown head gasket. Most of the time the head gaskets blow. The block isn't prone to damage - while alu heads on iron blocks isn't always an ideal situation, the OEM head gaskets are so weak, the gasket will go long before the ALU head can get a chance to overheat and warp! :P