THERMOSTAT - Please help!

[OBarbas]

I am a REAL NEWBIE with auto repairs.

My wife owns a 1994 Totyota Corolla. It overheated on the road, and the NRMA guy came in his truck and removed her thermostat. I wasn't around to see where it was installed. I bought a new thermostat and now am trying to figure out where it goes.

There are 2 hoses at the top of the radiator, a thin one leading to the plastic container I guess for excess coolant, and a wide black hose leading to the engine block. Does the thermostat go at the engine-block end of that wide hose?

One other question: my wife noticed when the car was overheating that the radiator fan was not turning on, i.e., the car was boiling, but the fan wasn't running. Would this have been caused by a faulty thermostat? Or did the NRMA guy, by removing the thermostat, just do a band-aid solution, and when I reinstall the thermostat, I'm going to run into overheating problems again because the real problem is something with the fan?

Thanks a lot for your help?

OBarbas in Sydney AUS

[project trueno]

locate your radiator, see the BOTTOM (lower tank) has a thick black hose as well? If you follow the route form there, you will find the thermostat. (The hose will go to the engine, and you will see 2 10mm nuts bolting on the small flange)

The thermostat, is not an electrical device, it controls the engine's temperature. The fan, is controlled by a thermostatic SWITCH, which is a electrical sensor threaded in your outlet water housing. When your engine gets hot that switch internally will close, and allow electricity to flow throughout your fan circuit. OF course there are also many causes of your fan not coming on, i.e. motor not working, fan circuit open somewhere/shorted to ground, fan relay faulty, etc etc

[4Aaron GE]

Dude, this is a 4A-FE. I'm pretty sure the thermostat is on the top on this one.

oh wait, you're in Australia.... Do you know what engine you have?


By the sounds of it, your problem might be electrical. First step would be to check your fuses. After that, maybe the switch/sensor that controls the fan? It should be located by the thermostat. Check the fan too, I guess.

[|PuNiSh3R|]

I can tell you most likely what the problem is.. as I've had the same issue on my 4A-F... that is, as long as the car was moving it wouldn't overheat.. good cooling system.. but if I came to a stop like at a fast food joint or something where I was sitting idling for a bit.. she would start to overheat n bubble.

The fans wouldn't come on and I had no idea why.. and then just outta no where they would start working again. Or sometimes when I was working on my car.. I'd put the key over to ON and the fans would come on .. both of them!

I pulled the thermostatic switch, which is on the water housing on the opposite side of the water pump on the engine. Follow the lower radiator water line to the water inlet housing. YOu will see a bunch of stuff there.. inside that housing is the thermostat.. what hapens is when the coolant is below 180F the wax in the thermostat is contracted and doesn't allow coolant to pass from the radiator into the engine. Once the engine begins to heat up and the water that is still in the engine block reaches over 180F the wax in the thermostat will begin to expand and open so that water from the radiator goes into the engine.
Ok, now at the same spot there is going to be a single wired plug.. it will probably be round.. it will go onto a long-ish plastic to metal piece that will go into the water housing.

Drain the radiator by either removing the lower hose or opening the drain cock on the radiator. Take that thermostatic switch out.. and replace with a new one.

In my case I couldn't find a new one so I said F this and I soaked the threads in acetone then cleaned the threads.. that did the trick.

[OBarbas]

Thanks so much guys for your help. I've had 2 solid days of pouring rain this weekend and the car's on the street, so I'll have a crack at it next weekend! Wish me luck! Thanks again!!

[hdsalinas]

while we are talking about thermostats...

My car is nearing 100k miles. So in the upcoming months as part of the 100k tune up I am going to flush the radiator. I have been recommended that since i am doing all this, to go ahead and replace the thermostat.

I have a 99 american corolla and I dont know if it uses the same thermostat as the corollas they sell here in Honduras.

Would any regular off the shelf thermostat, or one made for the previous model work fine in my car?

thanks