When does the thermostat open

[Thunderchild]

I have a MK4 fiesta (2000 endura-E engine) is it normal for the radiator to be warm when the engine coolant is at 73 C ?

note: temperature was registered on an OBD2 reader device not sure where the temp sensor it reads is in the engine. being 11 years old i suspect a broken stat

[TWR]

It should open when the car's temp gauge reaches 1/2 way Thunder. Its not a big job to replace, about 20 mins, but don't forget ti refill with Summer/ winter anti freeze.

[Thunderchild]

problem is I don't have a gauge and don't know what temperature half way up the gauge is equivalent to. I have an OBD2 code reader device that acts as an information screen on what is going on in the engine and tells me the things my dash does not like engine revs and coolant temp

[ChuckFickens]

Sounds a little low for the thermostat to open, high 80s to low 90s would be more like it...

The best way to check it though is to remove it and boil it in a pan and check what temp it opens at, you can't really trust just the rad being warm as an indication of the thermostat being open or closed as a lot of cars allow a little water to bypass the stat before it opens.

That said, if your going to go to the trouble of removing it you may as well just fit a new one anyhow as they only cost a few quid.

[ChuckFickens]

Seems that it's either going to be 88c or 91c
http://www.rockauto.c...2BSystem%2BThermostat

[Thunderchild]

I wonder where the sensor for the coolant temp that provides the OBD2 information is located. before or after the rad, or in the engine ?

[TWR]

Thunder, just put on your heater after about 3 / 4 mins, warm air should be coming through that will tell you if the Thermostat is working ok.

[Thunderchild]

can you clarify that ? do you mean that if my heater is not giving hot air because the rad is draining all the heat out the thermostat is opening too quick. I get hot air from easily when the system when it is over 60C but actually now you mention it it don't get that how anymore. Problem is I've only had the car 3 weeks so don't have experience to go on. I think I'm going to change the thermostat anyhow, like said before it don't cost much. I did it no probs on my mondeo so not scared to do it (just already poured money into the car).

[ChuckFickens]

Heater circuits normally bypass the thermostat on most cars.

[Thunderchild]

yes usually they are part of the engine circuit so that when water is going around the engine but not the rad it goes through the heater rad

[TWR]

The stat will cost you under a Tenner the job should take you 1/2 an hour, make sure you have a gasket before you start.

[Thunderchild]

yep all done. now engine gets up to 96 C before it opens and drops back down to 80 sometheing