Woke up this morning and drive the car in town and on highway for a total about maybe an hour with my radiator fan switch unplugged(thus letting the fan run non stop while the car is ON) and it didn't over heat at all or jump at all. It stayed at the 45% mark the whole time. So what I'm thinking what's causing the overheating may be something electrical and not mechanical? I'll have to test it like what everyone's been saying but I never have time to do it. I'll check back when I get the results.

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Thats what I think my problem is. The motors been losing compression since i got it 20k miles ago then it overheated one time and now it runs hot everytime i drive it

sounds like that thermostat, since you put a different one in to kick in at a cooler temp, it doesnt stay on as long as it would if it was the oem one. id say put the oem one in,

Ok. Finally had time to do the switch test and it passed. What I noticed yesterday was that There was a puddle of coolant sitting right on top of the fan motor. I thought it was odd so I wiped it dry with a napkin and let it idle for like 5 min and that same spot was wet again? What's confusing me is that the radiator is out of the box new and so is the upper radiator hose and the radiator cap. I inspected it and it seems like there's coolant leaking out from the INSIDE of the radiator hose where the inner thread is. My coolant reservoir was only half way full too. Now it's making me think if I have too much pressure? My Radiator cap pressure level is 0.9. That's the standard pressure level right?

What I think might be causing this is because I'm running the fan non stop to prevent my car from over heating so I'm thinking that the fan is keep my engine too cool so the coolant isn't getting hot enough to where the thermostat is opening to add some flow to the coolant? But I don't know though. That might just be my theory. I'm going to remove the thermostat tomorrow and run it like that for a while and see how my car runs.

maybe your thermostat is getting stuck, happened to me and cracked 2 radiators.have you done a compression check?i've heard even thought you don't got "chocolate milk" you could have a bad head gasket.worth a shot.

Let's start with something simple -- your radiator hose should not leak. Colder coolant exerts less pressure, but even if the pressure was high the radiator cap should release it.

The cap specs are, to my knowledge, standard opening pressure of 74 – 103 kPa (0.75 – 1.05 kgf/cm2, 10.7 – 14.9 psi).

The system, other than the cap, should hold pressue at least to 118 kPa (1.2 kgf/cm2, 17.1 psi ).

Pressure in the system is created solely by the expansion of the coolant as it heats up, not by the water pump. The gauge and the ECU readings come from the the temperature of the coolant in the engine, which circulates around the block regardless of the thermostat being opened or closed. The thermostat opening allows some of the coolant circulating in the engine to enter the radiator, and some of coolant in the radiator to enter the engine, circulating in parallel to the coolant in the engine block. The fan on the radiator will not provide any meaningful cooling to the engine block.

Observe the engine over a range of temperatures to see whether it leaks when cold or only when hot, and to figure out where it's actually leaking from -- that tends to be useful in figuring out what part is malfunctioning.

Removing your thermostat should result in your engine running too cold, since there will be nothing to keep the engine block coolant at proper operating temperature. Without a thermostat you should see the temperature drop as you drive, then climb when idling.

This post has been edited by Galcobar: Jun 27, 2012 - 10:35 PM

this is all pointless, tellin u from experience, first overheat is the start of cancer, the more you overheat the more you warp your block and head the less seal it makes the more it pushes out the coolant from the rad cap the more it overheats...... the cycle continues at an exponential rate.

in your instance it doesnt happen as fast in your 5sfe as it does in my 3sgte since you dont run as hot to begin with.

all these little things your doing is only prolonging getting to the point where your head and block are so warped they will never seal at all ever.

i also couldnt believe i had warped head&block&gasket i thought must be something i can fix.... upgrade to alloy radiator helped for 2 weeks it didnt overheat, but then wen it did.... it was nasty, and death. from then on overheated as soon as driven..

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This happened to me. New engine, on it's way.