10 replies to this topic

[petrolhead2047]

I have a 1994 Cooper spi that im slowly doing up. I have noticed that the temperatures sender is at the bottom of the radiator and not on the head, now surly if I was to have a water leak my engine would cook and I would know about it as there would be no water passing the sender to get a reading, Where as if the sender was in the head it would still pick up the engine temperature/over heating.
Hope this is making sense, it just seems silly to me.

There is a hole in the head where they put the sender on the carb minis as my friends is here. But there is no thread in it.
I would like to know if I could put one here if so how?

Any help or advise appreciated

[mrslaphead]

I think the one at the bottom of the rad is just for the temp gauge.
The one that is linked to the ECU is under the throttle body.

[xrocketengineer]

I think the one at the bottom of the rad is just for the temp gauge.
The one that is linked to the ECU is under the throttle body.

The one at the bottom of the radiator is the thermal switch for the auxiliary electric radiator fan located under the left wing.

[DaveRob]

The Coolant temperature sensor , as 'MRSLAPHEAD' correctly points out, is under the throttle body in the manifold .... this is the one that is monitored by the ECU ...and, via the ECU, works the temp gauge in the car.... its REALLY hard to see never mind get to to change..... in fact it is changed by REMOVING all the throttle body and unbolting the manifold..... You will need a new inlet/exhaust gasket and the sensor .... from memory.... is about £42 ea...... the one in the radiator isnt involved with the temperature guage in an SPI it is just an on off switch for the electric fan... and rarely works in my experience. If the temp gauge in the car dosnt read to the half way line then chances are its the coolant temperature sensor..... by the way... this affects the running of these injection cars in a BIG way.... if its faulty.... it NEEDS changing.... cause the next thing to fail after the CTS will be the Lambda sensor .....

Hope this helps

Rob

Edited by DaveRob, 14 April 2009 - 04:05 PM.

[mrslaphead]

I think the one at the bottom of the rad is just for the temp gauge.
The one that is linked to the ECU is under the throttle body.

The one at the bottom of the radiator is the thermal switch for the auxiliary electric radiator fan located under the left wing.

Thanks, was I right about the other one ?

[mrslaphead]

I changed the coolant temp sensor on mine recently and the sensor was about £13 , I think the air temp sensor
is the one that costs about £42,
It is very true about a faulty coolant temp sensor causing lambda sensors to fail as I also had to change that.

[xrocketengineer]

I think the one at the bottom of the rad is just for the temp gauge.
The one that is linked to the ECU is under the throttle body.

The one at the bottom of the radiator is the thermal switch for the auxiliary electric radiator fan located under the left wing.

Thanks, was I right about the other one ?

I have only messed with the bottom one. Used it to drain and flush the radiator. Easier than disconnecting hoses. Connected a jumper to the terminals and with ignition switch on, the fan came on. Took the switch and checked with an Ohmmeter and it would close (0 Ohms) with boiling water. It supposed to close within a few degrees of that.
I used WD40 to loosen the switch from the rubber seal the first time. Used a new seal for the final installation after the flushing cycles.
That is the extent of my knowledge.

[petrolhead2047]

Thanks guy you been a great help.

Back to what rob was saying. My temp gauge in the car dose not go over half way (well iv not seen it). So does this mean it’s not working correctly and need replacing?

[xrocketengineer]

Thanks guy you been a great help.

Back to what rob was saying. My temp gauge in the car dose not go over half way (well iv not seen it). So does this mean it’s not working correctly and need replacing?

Mine is a 1994 Japanese spec Cooper. I have owned it for about two months. The needle would go to the center mark (I assume normal) on the gage. I have not seen it go above that, even when it idled for long periods while doing the flushing. I had not noticed the electric fan coming on either. That is why I checked the fan and the switch. I had very rusty water in the radiator and had me worried. Apparently, the cooling system was fine all along. I hope it is even better now.

In order to read accurately the temperature sensor as the ECU sees it, you need a code reader connected to the ECU. That is my next adventure. I bought a Yikes! Pickavant (shipping is a killer) code reader and I am waiting for its arrival from the UK. From what I can tell, the ECU sends an output to the gauge on the instrument panel for the temperature reading. But I believe that gauge reading could be messed up (bad gauge/bad wiring) and the ECU could still be getting good data from the temp sensor.

Edited by xrocketengineer, 14 April 2009 - 11:48 PM.

[DaveRob]

if the gauge is reading about half way then its ok..... a bit under or just a tad over either way is fine.... if it only gets just above the blue then id suspect the Coolant Temp Sensor in the manifold. Its worth checking all the wiring for corrosion and all the joints to make sure they are good. Make sure your thermostat is the 88 degree one and that it actually operates at 88 degrees. Another sugestion is that if the car, when its up to temperature, idles at about 750 ish rpm then it suggests that the CTS is feeding a good signal to the ECU.... ( carefull because other things can affect the idle as well as the coolant temperature ), but if the idle speed is right then the ECU must have the right signals going to it. This post is worth reading if you want an explination of 'how it works'... http://www.theminifo...x...c=61469&hl=

Hope this helps

Rob

[xrocketengineer]

Wow, very impressive thread, Rob! It looks like rocket science to me!