Late v6 thermostat

[andmcit]

Not yet noticed the location on the one on my Xantia although a poster
on club-Xm has asked about one on his 1997 s2 V6 Xm. Anyone here
with experience that can help?

"Does anyone know where the thermostat is on the XFZ (ES9J4) engine?
It is not immediately obvious and mine seems to be either not there or
stuck open. but the top hose appears to come from an alloy casting that
joins both cylinder blocks, without an obvious bulge for a thermostat.
Thanks

TudorBrown"

Andrew

[CitroJim]

Oh yes,

It's on the side of the engine above the gearbox and a pain to get to Andrew. Access, as they say, is poor!

You can just see the thermosts housing in this picture, just to the right of the rightmost green arrow.



The cover comes off and it's all sealed with an O ring. 'Tis tricky. later I can post up some "official" diagrams.

The V6 thermostat is a funny old thing. Looks nothing like a conventional one at all..

Richard (DickieG) ran an article about it in his CCC "Xantia Files" a while back. If you have all your back issues of the Citeronian, you'll find it...

EDIT: In the picture, the gearbox has been removed for clarity

[xantia_v6]

... but the top hose appears to come from an alloy casting that
joins both cylinder blocks, without an obvious bulge for a thermostat.

It is behind that casting. On the Xantia, the generally poor access is made worse by the steel hydraulic pipes which run directly across the thermostat housing, and (at least for me) had to be bent to provide enough clearance.

The thermostat itself is somewhat unconventional and the water flow is controlled by a piston which slides in a large O-ring (purchased separately).

Don't trust the temperature gauge as a measure of the thermostat, the temperature sensor for the gauge is not located at the output of the thermostat, but is located so that it sees a mix of water being recirculated and water from the radiator, which means it always reads lower (sometimes much lower) than the temperature of the thermostat.

[andmcit]

Thanks fellas, information duly passed on and linked here. I'm learning
all the time myself about this engine I've got which I have barely had the
opportunity to accquaint myself with.

Andrew

[andmcit]

Fantastic help thankyou. I guessed it might be that bulge but with such poor access and apparently being on the return from the radiator I wasn't sure.

Thanks again.

Tudor

[lexi]

Thethermostat itself is somewhat unconventional and the water flow is controlled by a piston which slides in a large O-ring (purchased separately

Any data as to whether it is more reliable than a standard type?

[xantia_v6]

I replaced mine when I got the car at 60,000 miles, on the basis of the temperature readings, but I am sure there was nothing wrong with it, the new one behaved just the same. 95,000 miles later, the new one is still behaving just the same.