C5 X7 thermostat replacement

[Peter.N.]

First a couple of pictures of the thermostat assembly so you know what you are dealing with.

Thermostat front

Thermostat rear

Remove the air box and associated hoses, also the top intercooler hose, this will give you more room. Bolted to the top of the housing is a bracket that carries most of the wiring on that side, some of the nuts are difficult to see, a torch and mirror would be useful, you will need to pull it out of the way, I tied it back with a couple of stretchy luggage straps to keep it out of the way. You will also have to disconnect a couple of plugs

Bracket carrying cables

Cable bracket tied back

Three of the studs that hold the housing on have splined ends requiring a torx socket to undo, the reason being is that there is insufficient room to remove them from the housing so they come out with it.

WARNING anything you drop at the front of the engine bay will end up in the engine undertray. You have been warned!

Remove all the hoses, easier if you remove the studs first, several are difficult, the very back one is virtually impossible without the special tool, about 8.00 pounds on Ebay. When I reassembled it I used Jubilee clips, much easier to access especially with a flexible hexagonal driver. The pipe that goes across to the right at the back of the pump has a wire clip on the right hand end which is reasonably accessible, it pulls out upwards.

Tool you will probably need to remove rear pipe clip

With hoses removed

The impossible pipe

When refitting the pipes slide the Jubilee clips on to the connection and slide the hoses into them, if you leave them loose on the pipes they are likely to disappear down them never to be seen again. They also are available for not a lot of money on Ebay.

The radiator drain consists of a short piece of rubber hose with a blind end, just slacken the clip and pull it off - mine fell apart so I made one up.

There is probably a special Citroen coolant but I used red OAT as I had it in stock and its cheap. There is a bleed screw fitted to the front top pipe that needs to be transferred from the old pump, also the pipe that goes across the back.

Apologies for the pictures being in reverse order - its taken me most of the afternoon to load them in the right order. They are all titled though.

If I have forgotten anything or you need more information just ask.

I got the new thermostat assembly from Ebay for about 24 pounds, I compared the pictures with the more expensive ones and they all looked the same.

Peter

[Edited to place pictures in-line for clarity]

[xantia_v6]

Good work

Lets hope that this one lasts the distance...

[Peter.N.]

Many thanks to whoever edited it for me.

Peter

[osx]

Think I may have the same problem.
Could hear the radiator cooling fan spinning when i got out of the car and though that was strange as this doesn't usually happen even on a hot day. Today I got an engine overheating warning while driving (after about 10 minutes of motorway driving). Fortunately I was able to stop at a service station and after 10 minutes the engine had cooled down a bit and the radiator fans stopped spinning. Drove for another 10 minutes and the same thing happened just as I was parking. There is coolant fluid in the reservoir (lowish level but if there was I leak somewhere I would expect it to be empty). I also noticed that the heating doesn't work (blows cool air even when set to highest temp).
Anything else I should consider - any point running a diagnostic?

[xantia_v6]

If you have got no heating, I would suspect the water pump (or an airlock).

Does the X7 have a bleed pipe from the radiator to the header tank? if so, is there any water being pumped through it?

[GiveMeABreak]

Don't forget the possibility that if the engine is hot and the cabin is cold, that you may have a blocked heater matrix... this could be blocking circulation. Do of course check for leaks elsewhere as there may be other reasons for this. But if it starting to overheat, I really recommend you don't keep driving it or you could have a bigger bill.

[GiveMeABreak]

If you have got no heating, I would suspect the water pump (or an airlock).

Does the X7 have a bleed pipe from the radiator to the header tank? if so, is there any water being pumped through it?

Yes it does.

[osx]

Not going to drive it until it is fixed. Oil temp was ok even when I got the stop due to overheating alert.

[osx]

Oil cap is clean so at least the gasket is ok.

[osx]

Water pump was replaced last year with csmbelt. That's what I thought at the beginning.

[xantia_v6]

Water pump was replaced last year with csmbelt. That's what I thought at the beginning.

That doesn't guarantee it hasn't failed.

[osx]

But it will have warranty so that would be the good scenario

[GiveMeABreak]

If you can start looking for leaks then I might be able to provide some likely culprits once you have confirmed the area if there is a leak - otherwise the system maybe blocked / locked and therefore preventing circulation.

[osx]

Can't see a leak and there is coolant in the reservoir (level is low though). Any point topping up with water to see if it helps?

[white exec]

Unless you intend to completely drain the system again, best to keep tapwater out of it. It only introduces calc (sediment, blockage). Use distilled/demineralised water if necessary.

Cold heater, hot engine:
With engine fully warmed up, feel the two hoses/pipes leading to the cabin heater matrix - usually possible in the engine compartment. Both should feel hot. If one is much cooler thsn the other, that suggests a blockage (or no flow) through the matrix.

Water pump
On many engines, if you look into the header/expansion tank, and briefly rev the engine, you will see the coolant level there rise, then fall back when idle is resumed. This indicates that the water pump is functioning. Doesn't happen on all engines, though.
Again, some systems produce visible coolant circulation through the head tank, which will be visible if engine revs are raised for around 10 secs.