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Just to make you feel good...

Posted: Thu Dec 06, 2018 7:22 pm
by White Exec
And when we have to agonise about replacing the odd small but vital bit in one of our steeds,
spare a thought for the owners of a C4 1.4 VTi
who might need to replace their engine thermostat.

This is it...
C4 1.4 VTi thermostat-outlet assembly _r.jpg
Photo by Cutac on FCF

So who decided to wrap that small little stat in a Darth Vader helmet?

Re: Just to make you feel good...

Posted: Thu Dec 06, 2018 9:18 pm
by Dean
That is the ECU controlled stat isn't it? cool idea in principle but its a bit more than a tenner when it goes wrong...............

D

Re: Just to make you feel good...

Posted: Thu Dec 06, 2018 10:38 pm
by sageman
What’s the advantage over a normal stat

Apart from possably getting up to temp quicker for short jurneys/city traffic etc I can’t think of one

Re: Just to make you feel good...

Posted: Fri Dec 07, 2018 2:55 am
by xantia_v6
Speaking as someone who has replaced one (3-times, but that is another story) they don't have much advantage. The electronic control is only secondary, and they work just as well if you unplug the control signal (I drove ours for about 1000 km on purely wax-stat operation while waiting for a replacement).

The annoying thing is that there are at least 7 different versions, differing only in the position of the temperature sensor, the electrical connector shape and one heater hose which is sometimes a clamp seal and sometimes and o-ring seal. This means that when buying after-market, the wrong part is often supplied.

Re: Just to make you feel good...

Posted: Fri Dec 07, 2018 3:00 pm
by Woodie
Blimey i thought the one on my SAAB 9-5 TiD was bad... That cost £50 instead of £10 for a normal one on the petrol versions... I wonder if thats why they do it... Or am i being cynical :)

Re: Just to make you feel good...

Posted: Fri Dec 07, 2018 7:16 pm
by Dean
I believe the reason they do it is for emissions control and improved economy, i remember reading about it a few years ago when i stumbled across one fitted to a Peugeot cabby, i think the idea was that best engine efficiency was at X temperature but wax stats were too slow to operate and not very dynamic and therefore unable to reliably hold the engine at this high temperature without risk of overheating so wax stats were set to run at a lower temperature to protect the engine and sacrifice that little bit of efficiency.

In all likelihood you would never feel the difference without it as stated above.

D

Re: Just to make you feel good...

Posted: Sat Dec 08, 2018 6:49 am
by xantia_v6
The electronic control element is a 15 Ohm resistor which heats up the wax stat. It can only open the thermostat further, it can't close it. With the electrics connected or disconnected, the temperature gauge never wavered from 90 degrees.

Re: Just to make you feel good...

Posted: Sat Dec 08, 2018 8:28 am
by White Exec
I forget how many cars I've owned where the engine running temperature was correct and stable, without the need for this expensive and unreliable lump. The unit likely speeds up engine assembly on the production line, as it incorporates a good few components previously separate.

IIRC, a good few of these have had to be replaced under warranty. Couldn't have happened to a better... As said, a good little earner by way of out-of-warranty failures. One more component for Room 101.

Re: Just to make you feel good...

Posted: Sat Dec 08, 2018 9:32 am
by Dean
xantia_v6 wrote:
Sat Dec 08, 2018 6:49 am
The electronic control element is a 15 Ohm resistor which heats up the wax stat. It can only open the thermostat further, it can't close it. With the electrics connected or disconnected, the temperature gauge never wavered from 90 degrees.
Truely is a waste of time then..... why would you want to artificially open the thermostat i wonder?
Just had a look at replacement part costs and they dont look too horrific at about £30-£40 for pattern parts which isnt bad for the whole housing, stat and sensors, still not £10 for a stat and seal though.

I keep thinking about the practicality of an electric coolant pump and controller, i was speaking to a guy at a classic car show this year who had one and he raved about it, no thermostat, dynamic pumping and run on function means that a perfectly constant engine coolant temp can be maintained under any condition, he insisted it didnt affect the cabin heater warm-up but i would guess it would make the heater slow to get going in certain coolant system designs?
My water pump is perfect though at the moment so not something i would be motivated to do at this stage.

D

Re: Just to make you feel good...

Posted: Sat Dec 08, 2018 10:49 am
by White Exec
Likewise. I can leave home in the 2.5, drive immediately 500m up a hill which rises 50m, and by the time I get to the top there is useful heat coming from the vents. 1000m further on, everything is nicely warm. And that's in a diesel!