6G Celicas Forums

Car overheated other day and it was leaking, it is leaking out of the plastic white looking coolant low to full tank it has a whole right at the top, not sure if the hole is plugged on other celicas but it's leaking from there, the fans are not kicking on either everything else is fine, please show me pic of where the fan sensors are so I can get them from the junk yard

first check to see if you have fluid in the radiator.

Do you have a GT or ST?

the engine coolant temp sensor is on the right side of the engine, its a 2 wire sensor.

drained and filled the radiator, I have too much in as it is coming out of white over flow tank, so I need to drain some out, the fans will not come on what so ever, so radiator cap was bad, thermostat fine, fans will not kick on, so theres a problem with sensor now if that doesn't fix it, water pump, everything else, hoses, radiator, and etc all good to go, double checked everything today.

99 GT 5SPD

On the GT, the fan thermostat switch is located on the passenger side of the bottom tank of the radiator, right next to the lower radiator hose. It is a two wire plug, the conduit runs down the radiator support and fan shroud. If you unplug the wire from the sensor it will force the relays to kick on the fans. If the fans run nonstop when the plug is disconnected, the switch is bad; if the fans still dont kick on, either the relays or the fans are defective. The switch is literally either open or closed, open circuit(no continuity)= fans on; closed or short circuit = fans off.

The temperature sender unit (for the temp guage on the dash) and the coolant temperature sensor are located on the coolant outlet pipe near the distributor where the upper radiator hose exits the engine. The coolant temperature sensor has a two wire plug, it is used by the ECU. The temperature sender has a one wire plug.

Temperature Switch= Turns Fans on/off
Temperature Sender= temp guage on cluster
Temperature Sensor= ECU uses for F/A ratio

Kind of confusing that there are three of them, but the S-word in all of them determines their use. Many cars use only two or even one sensor to perform all these tasks, ours uses 3

Let us know what happens when you disconnect the two wire plug from the bottom of the radiator, then we will be able to advise you on the next step in diagnosis or repair.

This post has been edited by Special_Edy: Jun 6, 2014 - 10:21 AM

nailed it!!!!

if your fans aren't coming on the coolant is getting hot enough to raise the pressure above the setting of the radiator cap and blowing it back off. this does not indicate you have "too much fluid", the radiator system should be completely full.

So news new thermo, new timing belt/water pump kit being installed tomorrow I already have everything off and then, no leaks in the top or lower radiator hose, the fans work, if I still overheat tomorrow like I think will happen, what's next? No coolant is leaking internally my motor oil I changed while over heating period to make sure, so I know it's not going to be a head gasket, my next guesses would be, one of the sensors, radiator itself, or one of the metal pipes runs from heater core and 2 where the thermo is, could have busted one, but I don't wanna buy parts and not have it fixed

No need to change the timing belt or water pump. These two component only fail catastrophicly. A faulty water pump will begin leaking through the bearing, which will cause coolant to drip through the 'weep hole'. You will begin to hear loud squeeling if this is the case and notice coolant coming from the timing cover. The timing belt can potentially snap after MANY years of service and its 60k mile service interval, unless there is a major engine(or water pump) disaster which breaks it. The engine is non-interference so there will be zero damage caused by a snapped timing belt. Save yourself the money and dont replace them unless one fails or you have a good reason to tear the front of the engine apart.

A failed headgasket will not always leak coolant into the oil, it will often just blow compressed air into the coolant system. This highly compressed air will force the coolant out of the radiator cap and overflow exactly as the syptoms you have described.

A leak from the radiator, hoses, heater core, water pump or any component in the coolant system will NOT cause coolant to overflow through the radiator cap.

This Is the way mine is acting. The exhaust gas leaks from the head gasket into the coolant and over-pressurizing the radiator system and blowing coolant off out of the overflow hole.
There is no coolant on the spark plugs, and only small traces of oil in the radiator, it only loses 1 quart a week, and really isn't that bad unless you spin the motor up real hard. There is a test that can prove if you have exhaust gasses in the coolant, search it on YouTube.
If your thermostat, waterpump, and fans are working right then you probably do need a head gasket.
I'm buying a used head so I can send it t the machine shop to be worked on ahead of time and be ready to put on before I take the old one apart.
If you try to replace the gasket without resurfacing the head it won't be right.
It's about $135 for a head and maybe another $100 for the machine shop

This post has been edited by VavAlephVav: Jun 10, 2014 - 12:08 PM

Just update new water belt and timing belt was installed, bled system, added 50/50 coolant, filled overflow just to the low level, idle 15 mins with climate control turned all the way to the heat or red, drove and tested car, no more over heating, problem solved! Close thread please

I'd keep checking your coolant level every 2 or three days until you are sure its not loosing any more fluid.
basically if you've overheated the motor, the aluminum head is probably warped slightly and causing your problem.
they say if you put a metal ruler across the surface of the head and try to squeeze a feeler gauge under it only takes a .5 mm gap for it to be bad.

I will, the reason I was overflowing out was because my radiator was completely filled and the overflow tank was filled all the way filled to the top like how washer fluid is suppose to be I'll test it but I honestly doubt it, when I originally overheated there was like no coolant in my car and I drove it home slowly by stopping cooling down etc multiple times, but I'm lucky that radiator didn't crack, anyways it's all fixed now I'll check it but my car is running like a champ now better than it ever has since I've had it.