A general thermostat query.....

[milleplod]

When shopping around for a new thermostat for my '09 HDi C5 (136), I noticed various suppliers listing both an 80deg one and an 83deg one as being correct. Which one would my car have had when new, and would it make any difference if the 'wrong' one was fitted?

Pete

[GiveMeABreak]

If it's the Water Temperature sensor you need Pete, it's part 1338C1 for your car and DIAM 25,4 LONG 53

[milleplod]

Evening Marc.

I think we're at cross purposes! I've bought a new thermostat for my car, part number 1336Y9, which I think is an 80deg one. Some cars seem to have 1336AS thermostats, which I think are 83deg ones. Some sellers on eBay don't seem to differentiate between the two, and sell thermostats that they claim cover both part numbers. I just wondered if (other than the obvious opening temperature difference) the wrong 'stat could cause any problems.

Pete

[GiveMeABreak]

Yes, we are definitely at cross purposes Pete

Part 1336 Y9 is actually the complete assembly Pete - (Engine Water Outlet Tank).

Part 1338 C1 that i mentioned in my previous post is the actual temperature sensor:

Click Picture to Zoom

So if it is the complete housing you need - I would try and get the correct one 1338 C1 - as these 'equivalent' generic ones can fit many vehicles.

[EDC5]

Just as an aside, is there any reason why PSA vehicles' thermostats run at about 80 degrees vs the 90 degrees of virtually every other car on the market? I remember this even with my project 306 with an XUD9?

[milleplod]

Either the plot is thickening....or I am!

As per my other 'stat thread re the car taking a while to get warm/not getting as hot as it used to, I've bought £50-worth of 1336Y9, thinking that was the only way of getting a new thermostat. Am I right in thinking I could have just bought less than £10-worth of 1338C1, and that would sort out my problem?! Or do I actually need the complete housing as the thermostat is buried inside it? The complete unit is returnable though, so all is not lost if I don't need it.....

Pete

[GiveMeABreak]

Yep, the water sensor is available as a separate part and about £5 ish Pete, as you can see on the diagram.

That’s what was confusing me as to why you would want the whole thing

[xantia_v6]

The sensor, which is clipped in just sends a temperature signal to the ECU. The thermostat which controls the water temperature is moulded into the housing.

[GiveMeABreak]

That makes more sense.

[Paul-R]

Marc

The query is all about the thermostat not the temperature sensor.

Pete is wondering about the temperature at which it operates. Should it be 80°C or 83°C as he has seen both listed a being correct.

Separately EDC5 is wondering why they aren't 90°C as virtually every other car he is acquainted with is.

[white exec]

Still interested in why such a chilly thermostat would be fitted. Normal 'stat temp for coolant leaving a cylinder head is 88-92-ish.

[RichardW]

83 seems to be opening point for the 1.6 HDi thermostat too. Unlike 70 which is what the current one on my car opens at at present....!

[411514]

At a guess I would say 83 degrees is correct - that is the temp of the thermostats fitted to all three of the Citroens I have had. I wonder if the 80 degree units are slightly iffy pattern parts?

I wouldn't have though however that there would be any noticeable difference between the 83 degree and 80 degree 'stats. I can't imagine for one moment the 83 degree 'stat opens at exactly 83 degrees. I should imagine the error bound, at least after a couple of years use, is probably best part of 10 degrees either side of the stated temp.

[Mandrake]

Wax pellet thermostats are not accurate enough for 80 or 83 to matter in the first place!

The temperature still varies a lot more than that with changes in load due to the fact that the thermostat is only a proportional device, thus suffers from "offset error"... more heat produced by the motor means more water flow is needed to cool it, more water flow requires the thermostat to be open more, to open more it needs to be hotter! So it is really a sliding temperature range not one specific temperature.

[white exec]

OK, but why such a low operating temperature?
Perhaps the large plastic thermostat housing (outlet tank) can't stand anything higher???