The heater on my Xantia 1.9TD just will not give out enough heat despite:-1) Fitting hotter thermostat (90 Degrees I think)
2) Fitting new radiator
3) Flushing system
4) Bleeding system via the 'tyre valve cap' at highest point on system using header tank as top up.
On this last point how can a system work when the expansion tank (which becomes the header tank when car is in use) is lower than the bleed point?
When hot, excess coolant will be expelled from the expansion tank-air will take its place on cooling-water in the system will find its own level meaning that there will be air at the bleed location always.
Does the system rely on there being a vacuum within the expansion chamber on cooling? If this is the case could my rad cap be at fault?
Have I just answered my own question?
So many questions - So few answers
Sorry for going on - Any thoughts on the matter greatly appreciated.
Regards to all - Tom
Feeble Xantia heater
Moderator: RichardW
The system can work with a low expansion tank when the engine, and water pump, are running.
There is supposed to be a vent valve on the top heater hose, the highest point of the cooling system.
On the diesels, it's out of sight, behind the engine, and can only be found by 'feel'.
To vent all the air out throught the top vent valve, the engine must be idling, so as to push the water, and air, upwards.
If both heater hoses are about equally warm, it means that the hot water goes through them, and there is no air lock, and then the fault may be in the vents and motorised flaps, or even the fan motor.
The system relies on there being no air high up, that's in the heater hoses, so as to reduce pressure increase when warming up to avoid spilling coolant through the expansion tank.
On cooling, there is a vacuum that draws air into the expansion tank.
That must be left so, otherwise any top-up will again cause spill at warm-up and expansion.
The expansion tank must have room for at least ½ a litre of air when cold.
The radiator cap is not faulty.
If it was, it would spill coolant when hot.
There is supposed to be a vent valve on the top heater hose, the highest point of the cooling system.
On the diesels, it's out of sight, behind the engine, and can only be found by 'feel'.
To vent all the air out throught the top vent valve, the engine must be idling, so as to push the water, and air, upwards.
If both heater hoses are about equally warm, it means that the hot water goes through them, and there is no air lock, and then the fault may be in the vents and motorised flaps, or even the fan motor.
The system relies on there being no air high up, that's in the heater hoses, so as to reduce pressure increase when warming up to avoid spilling coolant through the expansion tank.
On cooling, there is a vacuum that draws air into the expansion tank.
That must be left so, otherwise any top-up will again cause spill at warm-up and expansion.
The expansion tank must have room for at least ½ a litre of air when cold.
The radiator cap is not faulty.
If it was, it would spill coolant when hot.
2002 C5 2.0i AL4 230,000 km 76372389