Dvinhie

For a while now ive been leaving my lexus es300 1997 at home since couple month ago my lexus es300 overheated but luckily i pull over before it went to hot. So this week i had time to check all the relay,replace two ect switch no 1 and 2 and themostat. Yet the fan still won't turn on only when i turn on the ac both of the fan goes on. i notice the coolant get so hot that it boil up. i had to disconnect the ect switch no 1 harness so the fan can keep it cool from overheating. so what can be the problem can anyone help? I would appreciate a lot and thank you.. i wouldn't want a car fan running all the time because it my 2nd time of having the fan replace within less then a year

Dvinhie

Can someone help me out?

Hayk

iTrader: (1)

I will try to see if I can find a trouble shooter for this issue as it's very interesting. From my basic knowledge of cooling systems, there is a switch that triggers the cooling fan when the coolant reaches a certain temperature. There are a few possibilities for your issue:

1. Coolant doesn't reach the appropriate temperature.
a. Your temp gauge is wrong
b. Sensor is reporting the wrong temp

What do you mean when you say it boils up? How do you determine that it's boiling? Are you opening the cap to take a look?

2. The switch is defective and needs to be replaced

3. There is an Open Circuit going to the switch. ex.: Broken/missing wires, unplugged components.

Couple of thoughts:
A defective thermostat should not stop the fan from turning on, because your engine is overheating. I'm not familiar with ECT Switches, I would like to find out what they're responsible for.

Questions - Where did source your replacement parts? How many miles on your 1997 ES300? Has the coolant been replaced recently?

LeX2K

Does your car pass these tests?

Hayk

iTrader: (1)

Thank you, Lexus2000!

I would recommend using an OBD2 scanner to read the coolant temperature, but I doubt the OP has one.

Dvinhie

yeah my car pass all these test

Dvinhie

yeah i open the cap and i can see the coolant have smoke coming out even when i close the cap i see the smoke coming out of the radiator cap.... i brought all my stuff basically from autozone. i replace the themostat so that seem that doesn't seem to be the problem. also those two engine coolant temperature switch on the bottom of the coolant and to the right side of the themostat coolant i have change both of them but I haven't changed out the two switch on the left side since i don't see it on the cooling system manual. im still confused how it only run when i turn on ac.... yet when i turn it off there no fan running and it will boil up coolant to the radiator cap.my car is at 270k right now

Hayk

iTrader: (1)

I may be wrong but I think you're not letting your coolant warm up to engage the switch. The cap helps pressurize the cooling system, so it's normal for it to smoke/boil when you open it while it's hot.

You said your car passed all the tests, but I think you skipped a few steps.

Did you burp all the air bubbles out of the system, when you did all that work? Run the engine without the pressure cap for about 20-30min, until the fans kick in. Also set your heater on the highest setting and turn off the A/C button.

Lastly, turning on the A/C will always trigger the fans to come on. That's normal.

Dvinhie

Hi there i did try what you told me to let the radiator cap open and burp for 30 minute but there still no chance the fan kick on. I even put back in the cap. With or without the cap the coolant still boiling up into smoke on the place where i pour the coolant. Is the fan suppose to be turn on and off when i put the key to ignition on? Because i dont see no fan even kicking on when i put in the key.

Hayk

iTrader: (1)

The fan does not turn on when you turn the key, it only reacts to temperature.

At what level was your temperature gauge, when the coolant started smoking? I still don't understand what you mean by boiling up into smoke. Could you upload a video?

It could be that your system is burping air or on the other hand, air or exhaust gas is getting sucked into the system. A bit of smoke is normal when the coolant warms up.

This might just be out there, but it's possible that your head gasket is damaged (a result of overheating) and it's letting exhaust gases into your coolant - which is what's causing the bubbles and smoke. Get a Head Gasket Test Kit, and check for presence of exhaust gases in your coolant.

Dvinhie

my temp gauge is in the middle when it come out of smoke with the radiator cap on.however if i unplug the ect switch 1 on the bottom of the radiator then the fan would run all the time to the point there no smoke or boiling on the radiator cap. thank you for trying to help me out and yet still not give up on my car haha : (

Dvinhie

I replace almost everything and do every procedure. Ect switch 1,2 , coolant burp , thermostat , relay. could there have something to do with an ecu or water pump or power steering pump?

Hayk

iTrader: (1)

Water pump is definitely a possibility, but in that case your fan should still be coming on if the car overheats.

How many miles are on it and when was the last timing belt/WP replaced?

You should check your top and bottom hoses. The top one should be hot and the bottom should be cold, if there is flow in the system. A bad water pump or a clogged radiator will stop the flow of coolant, causing the engine to overheat.

Best advice I can give: give the car to a mechanic and explain what you've already done.

Dvinhie

brought to one of the mechanic earlier this week and he have no idea what is wrong with it after all the testing he did... : ( am i out of luck?