DIY: 1998 V70 ECT (Engine Coolant Temp) Sensor Replacement

[badaitimur]

I don;t know of a way to do what you ask about.

However, consider that for a 50-50 mix of coolant and water, the boiling point is indeed about 105 C. But the cooling system is under pressure, and that additional 10-15 psi will raise the boiling point another 20 degrees or more. So the coolant never gets even close to boiling over as long as the system is kept under pressure, as it is designed to do.

To make the car run a little cooler, you could use a thermostat rated to open at a lower temperature, that would help.

Originally thermostat use 90C, i think it is not suitable for malaysia. some of my friends which own V70 2.0T, they has overheat problem twice and more..
then they change the thermostat OEM german made, 87C..

i also use that 87C's thermostat. while driving in highway, then monitored by OBD2 application, temperature remain about 87C-90C..but in idling mode (traffic jam), the temperature reach untill 105C before its decrease to 95C after cooling fan is on..

[badaitimur]

Helo, i'm Badai from Malaysia. Currently using Volvo S70 2.0T year 2000. This is rare model in US or EURO because i think this model for Italy's market, due to high price for road tax policy, its has same issue with Malaysia.

So i want to ask about the engine coolant temperature (ECT) sensor. according from this forum state the ECT will trigger cooling fan on/off.

I have OBD2 tools (android application), i have monitored and its seems the fan just on when temperature reach at 105C and off at 95C. I dont know its normal or not. But Malaysia's weather is too hot to accept that cooling fan trigger on at 105C. Its boiling level..!

so, may i know if i can change the ECT sensor that will trigger ECU to on cooling fan about 85C-90C? i don't interest to play with the ECU by change the ECT's resistance.

or, if we have another solution to makes ECU trigger the cooling fan more early., about 90C.
tqvm.

something like this..
but there are problem to find out voltage injected to PCM..
--> http://www.autospeed.com/cms/article.html?&A=112691

[cn90]

For your Malaysian climate, you can use the 87C thermostat, just like this:

http://www.rmeuropean.com/Part-Number/Thermostat-(87-deg-C)-__27166487_WAH_91DEFFEE.aspx

PS: Search forum for "stripped tstat bolts". Get new Torx bolts before doing this job!

[badaitimur]

Tqvm..
I've used that 87C thermostat already..

[badaitimur]

May I know if somebody may help me. Coz I'm looking for ECT circuit diagram. Its very helpful to find out the manner of voltage accross the ECT injected into the PCM either same port or another port of ECU. Then I've an idea to play with the ECU to switch on cooling fan at certain temperature based on our needs..

[cn90]

The circuit diagram is in forum, search for it.
But you are wasting your time dealing with output section of the ECU.

Focus on the input (thermostat and the ECT), which is easier to manipulate.
You cannot even change the ECT design so, the only simple way to manipulate the input is a "colder" tstat as I mentioned above.

For your Malaysian climate, a tstat in the range of 82-87C will be fine.

[cn90]

Tqvm..
I've used that 87C thermostat already..

Vernet makes a 71C tstat if you are interested:
http://www.rmeuropean.com/Part-Number/T ... 644EB.aspx

[badaitimur]

The circuit diagram is in forum, search for it.
But you are wasting your time dealing with output section of the ECU.

Focus on the input (thermostat and the ECT), which is easier to manipulate.
You cannot even change the ECT design so, the only simple way to manipulate the input is a "colder" tstat as I mentioned above.

For your Malaysian climate, a tstat in the range of 82-87C will be fine.

Tqvm.
i agree about the manipulate the input is "colder". i'm trying to cheat the ECU by manipulate the ECT's resistance. And for the thermostat issue, i think it just release water from the engine into the radiator at certain temperature. Then the cooling fan will performs to cool the water. Even if we use the lowest temperature of thermostat's characteristic, it's not mean water can cold itself. And from my observation, the cooling fan just on when ECT sensor reach at 105C. So its not solve my problem especially in traffic jam (idling mode).

[cn90]

The 71C tstat will solve your problem.
For Malaysian climate 71C tstat is fine.

[mindshadow]

So, the part that connects from the car to the ECT broke. It was old and corroded to the ECT, so it crumbled when I removed it. Anybody got a part number or something so I can replace it?