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Discussion Starter #1 (Edited)
My car's been over heating on me as I stated in another thread. So I've checked just about everything and anything I can think of. I'm now at the point that I believe it maybe the Temp sensor.... I'm just wondering how I can go about testing that. Also I can't seem to locate it.
 

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depends on what sensor you are trying to test, and what the car is doing.

what tools do you have available to you?

the one that turns the fan on is in the thermostat housing, follow the lower radiator hose to the engine, thats your thermostat housing, the 2 wire switch is the "fan control switch" although most people call it the temperature sensor.

the quick easy way to test the fan circuit is to either ground the green wire on that sensor. if the fan comes on the power side of the circuit is good. now unplug the connector and jump the green to the black, if it doesnt come on you have a bad ground (most likely thermostat ground). if the fan still comes on with the green and black jumped then the ground side of the circuit is good.

there really is no need to test the switch with a DVOM unless you really want to. if you test the circuit like i stated and its good then you have a bad switch or a stuck shut thermostat. i recommend replacing both at the same time. to actually test the switch/sensor you need to know what the resistance is at a particular temperature, i can get those numbers for you if you really want, but like i said really no need.

now if the fan doesnt work by jumping the switch/sensor's connector then you have a blown fuse or bad relay, or a bad fan motor. check for power and ground at the fan connector with the fan control switch jumped (green and black wire). usually a blown fuse is because of a failing fan motor drawing excessive amperage.

about 50% of the time its a bad thermostat causing overheating and no fan operation, the rest of the time its either the fan or the switch, or someone messing with the wiring or something.
 

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Discussion Starter #4
I suppose I should of given more details. Things I've tested so far.

Removed the Thermo stat and replaced the gasket.
Flushed the radiator and replaced it with 50/50.
System was presure tested and radiator is not leaking.

I've checked the oil and it's not milky and shows no signs of having coolent in it. A compression test was 135, 130, 145, 140 which may seem low but.. the motor has eagle rods and vitara pistons which is a 7-5-1 compression I believe. The car doesn't run any different at all even when it's over heating. (I don't allow it to get crazy)
 

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Since you said that you have a vitara setup are you boosted or just running NA until you boost? Are you running a fuel management system like Neptune or Hondata? I was going to suggest that if you are thinking that your temp gauge is giving in problems to just monitor your datalogs.

But if you don't have something like that then is your coolant overflow tank boiling over when you overheat?
 

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Discussion Starter #6
Since you said that you have a vitara setup are you boosted or just running NA until you boost? Are you running a fuel management system like Neptune or Hondata? I was going to suggest that if you are thinking that your temp gauge is giving in problems to just monitor your datalogs.

But if you don't have something like that then is your coolant overflow tank boiling over when you overheat?
My car is boosted yes. The car's been tuned on Neptune but the car was not tuned in my ownership. My coolent tank isn't operating abnormally.

What's weird is.... yesterday I was driving the car and it overheated. I pulled over and let it sit for 5 minutes because I was close to my house. I started the car back up and began driving and noticed the temp gauge started moving up again.... then it just dropped back to normal driving temp..... it was odd but the car has done this before. I'm at a bit of a loss.
 

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buy a new radiator cap, and make sure your overflow tank has coolant mix in it. fill it at least halfway and be sure the hose to it actually is submurged in the coolant

the fan switch might not operate either. when its running hot, does the fan kick on at all?

also try replacing the coolant sensor that is mounted under the distributor on the head. check connectors for corrosion and clean as seen fit
 

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Discussion Starter #8
buy a new radiator cap, and make sure your overflow tank has coolant mix in it. fill it at least halfway and be sure the hose to it actually is submurged in the coolant

the fan switch might not operate either. when its running hot, does the fan kick on at all?

also try replacing the coolant sensor that is mounted under the distributor on the head. check connectors for corrosion and clean as seen fit
The fans actually on a switch.
 

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not a good idea. before the temp gauge EVEN shows a temp increase, your coolant is ALREADY too hot.

wire in a thermostat from autozone or oriellys. cheap, and with a 160 or 170 degree switch, will be fine
 

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Discussion Starter #11
not a good idea. before the temp gauge EVEN shows a temp increase, your coolant is ALREADY too hot.

wire in a thermostat from autozone or oriellys. cheap, and with a 160 or 170 degree switch, will be fine
So wait. You're saying the reason I'm overheating is because I don't have a thermostat in the car?
 

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no. it means YOU cannot properlyknow the timw that is goood to turn the fans on.

either buy a fan thermostat kit, or install an aftermarket 160 or 170 degree thermostat in the stock place
 

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Discussion Starter #13
no. it means YOU cannot properlyknow the timw that is goood to turn the fans on.

either buy a fan thermostat kit, or install an aftermarket 160 or 170 degree thermostat in the stock place
From what I understand putting the fan on a switch is rather common. How would me having the fan on at all time's make my car get hotter then normal.
 

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when did yoy ever say its on all the time? since you didnt say it, i assumed you tried to guesstimate best time to turn on
 

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I suppose I should of given more details. Things I've tested so far.

Removed the Thermo stat and replaced the gasket.
Flushed the radiator and replaced it with 50/50.
System was presure tested and radiator is not leaking.

I've checked the oil and it's not milky and shows no signs of having coolent in it. A compression test was 135, 130, 145, 140 which may seem low but.. the motor has eagle rods and vitara pistons which is a 7-5-1 compression I believe. The car doesn't run any different at all even when it's over heating. (I don't allow it to get crazy)
this might be your problem if you removed the thermostat then the coolant is constantly flowing and will not have any time to let the radiator do its thing
 

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this might be your problem if you removed the thermostat then the coolant is constantly flowing and will not have any time to let the radiator do its thing
Ive tested this

this is a wrong idea

the radiator can keep up jsut fine

the PROBLEM with this method, is your motor will run cooler then it should, and can get stuck in loop, hurting gas mileage, power, and emissions


this does NOT cause overheating

whoever told you ahs NOT tested this


if its overheating without a thermostat REPLACE the radiator cap or radiator. the radiator can be clogged partially, and still allow some passage.

a bad cap doesnt hold pressure and flow is slow because of it. havent you ever wondered why aftermarket high pressure caps reduced operating temperatures?
 

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So your telling me the excessive heat that a turbo system generates will not heat soak the radiator to the point it no longer can cool now I have dealt with a bad cap before causing overheating but in the cars I have had that problem in the coolant boiled out the cap and not in to the recovery tank
 
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