Xantia TD Estate overheating

steveh · Post by **steveh** » 26 Nov 2005, 11:58

For about 6 months I have been having problems with my wifes Xantia 1.9 TD estate overheating, so much so that think the only thing it could be is a HG gone or warped head, probably both, however reading all the other Citroen related problems on this site it might be something as simple as me not filling the coolant level properly. The only symptoms are that after a while the temp gauge slowly rises from 80 upto 90 / 100 then I can see steam coming from the bonnet , it has happened so many times now that I know it is water coming out of the expansion tank cap. I have fitted a new cap but this made no difference. There are no leaks anywhere, I have had a new radiator fitted, the heater works fine, no water in oil, nothing coming out of the exhaust, in fact the only symptom of a HG is the water coming out of the expansion tank, but this could also mean a lot of other things too. Reading the queries on this site, I have never used a header tank to fill the cooling system (as recommended I should do) so could something as simple as that be causing all the trouble. The top hose from the radiator is usually rock hard which tells me there is a lot of pressure in there, is that normal? I can only ever find 1 bleed nipple, when I have finished topping up the system (again) I let the engine run for a while then open this and a lot of air and then air/water comes out but then when I close it again I can feel the radiator hose rapidly pressurising again and hence I am getting air in the system from somewhere. Anyone help?

Thanks Steve.

Clogzz · Post by **Clogzz** » 26 Nov 2005, 12:24

The important bleed valve is on the heater hose, the highest hose towards the back of the engine, to the left of the LHM tank as you look under the bonnet from the front of the car.
If the top radiator hose stays relatively cold despite the pressure in it, the thermostat could be stuck shut.
There are recent threads on the subject, and I'll post the links when I find them.

Found one since:

http://www.frenchcarforum.co.uk/forum/v ... ht=#104337

The important vent valve is in the white square in the second photograph.
The thermostat is inside the bolted cover under the yellow square.

steveh · Post by **steveh** » 26 Nov 2005, 14:05

Thanks for that, I have printed picture but it's not ther same layout as wifes car. still can only see 1 bleed nipple. Radiator hose when pressurised is hot.

Clogzz · Post by **Clogzz** » 26 Nov 2005, 15:29

One bleed nipple is a tyre valve cap at the top of the thermostat housing cover, where the top radiator hose goes.
Slightly to the top left of it is also a metal bleed screw with a hexagonal slot for an allen key.
Depending on the model or vintage, there is also a tyre valve cap at a T-junction of 3 hoses less than one inch thick.
The main bleed nipple is on the top heater hose, which is over an inch thick and disappears behind the engine into the firewall.

JohnT · Post by **JohnT** » 26 Nov 2005, 16:13

First job surely is to test the thermostat? If your head gasket was at fault it would be pushing out the coolant constantly if the leak was on the pressure side, or contaminating the oil therwise? These radiators are known for causing problems. If your theremostat is OK you should be getting heat from the complete area of the radiator if it is OK.

Post by **Peter.N.** » 26 Nov 2005, 17:44

If it only overheats when being pushed hard it will probably be the radiator, if it overheats when driving gently, and not sitting in a traffic, jam it will probably be the thermostat as allready suggested. A leaking head gasket would not normally cause it to boil but if you allow it to boil you will very soon need one!

steveh · Post by **steveh** » 26 Nov 2005, 22:09

Thanks all, I will try and find more bleed nipples and get the thermostat checked, it does tend to overheat if the car is stationary but it takes a bit longer, if she puts the heater on in the car the temp starts to fall. So is the pressure in the big hose normal?

Clogzz · Post by **Clogzz** » 27 Nov 2005, 12:05

steveh wrote:if she puts the heater on in the car the temp starts to fall. So is the pressure in the big hose normal?

If the heater causes the temperature to drop, it means that there's enough water passing through it, and therefore you don't have too much air in it, and it's not an air bleed that will cure the fault.
The pressure in the hose is not normal, there should only be a slight pressure, if any.
It looks like the thermostat is stuck shut, and will need replacing urgently.
The radiator hose goes to the thermostat housing cover, that needs unbolting to find the thermostat inside.
As an experiment, you could remove the thermostat and bolt the cover back on, to see if it runs cool without it.

Beware of all that overheating.
You're at a very great risk of warping the head and blowing the head gasket, costing big bikkies to fix.
The high pressure in the cooling system may also cause the heater matrix seals to leak.
If that needs fixing, the dashboard must come out, and it's nearly a full day's work even for well-versed experts.

There's no talk anywhere of cooling fans.
Are they spinning when the engine gets hot ?