Water In Header Tank.

[Guest tomrostron]

it seems i need to top up my header tank, a couple of times a week. is this normal. 2.1td. 1999. tom

[Guest Colin Hunter]

Hi Tom.

 

No, it's not normal to have to keep adding water so something must be amiss, OR you're filling the system too full and it's ditching what it doesn't need. Remember that water (and most other things) expands when heated and if the tank is absolutely full when the system is cold, it will release some when it heats up and the tank will seem to have lost some coolant next time you check it.

 

Alternatively, you may have a leak some where. Places to check include all pipe joints and clips, the radiator itself, and if you check inside the car for a sweetish smell and possible damp carpets, the heater matrix may be the cuplprit. Another possibility is the head gasket which may be on the way out. Another favourite on the XUD is the plastic moulding which forms part of the water pump. This can crack and leak as the vehicle ages.

 

If you have any mates "in the trade" see if you can borrow a pressure tester. This is coupled onto the header tank filler cap with the requisite adapter and the system vcan be pressurised (COLD) to 15 psi (1bar) or so. If there are any external leaks this should definitely show them up. If you can't see any drips then it may be the start of the head gasket going.

 

However, if the fluid loss stays much the same as it is now, I'd be inclined to leave things alone until it presents itself obviously and can then be dealt with.

 

Cheers. Hope this helps. :blink:

[Guest Peter Mann]

Hi Tom,

Colin is generally right, and gives a good strategic approach to loss of coolant.

But I came to grief in a different way in my 1994 2.0i.

On my Xantia, the cap to the header tank is quirky ; unlike any other I've seen. And therein lies a possible answer. The cap is sealed when it is in the centre position. At one end of rotation, the cap comes off, and at the other end of rotation allows venting of pressure.

If you have been leaving the cap in the venting position, and are using water or a low glycol mix as coolant, it can happen that the engine will cough coolant out after she has been turned off. This happens because the stored heat in the engine continues transferring into the coolant trapped in the water jacket, and unless you have 50% or more glycol, it will tend to boil, and spits coolant out past the loose cap while you are having lunch in the pub. Do this often enough, and sufficient coolant can be lost to put the head at risk of overheating.

The hidden danger in this is that if the cap is sealed in the centre position, and the coolant in the water jacket boils, the pressure builds up in the cooling system to the point where it disrupts the seals in the heater matrix, and you end up with the famous and expensive puddle in the passenger footwell.

Although the cap has a pressure relief set at 2.2 Bar (about 35psi), this pressure is too high for the heater matrix. ;)

Citroen solved this by specifying that coolant must be at least 50% glycol, but experienced drivers like me who have gone for decades in a mild climate knowing full well that a soluble oil in water coolant is both cheaper and better at resisting corrosion can get caught in this subtle trap.

So, if your cap is loose, do not seal it unless you are complying with the high glycol anti-boil coolant specification, or you can end up with a whole new problem.

[techbod]

a pressure test or a dye test will show where the problem is but a little advise on antifreeze is don't over mix it as if cause a phantom fault code when the problem is only that the water cant heat up to the correct temp

[Guest Peter Mann]

A pressure test or a dye test will show where a leak is. A pressure test will not show a leak if the coolant has been escaping past an incorrectly fastened header cap.

Glycol has no ability to refuse to absorb heat. Its function in the cooling system is to prevent freezing of the coolant when ambient temperatures fall below zero Centigrade, and to prevent boiling when the temperature goes above 100 Centigrade. The higher the proportion of glycol in the coolant, the higher the fluid temperature can go before boiling begins.

Considering the fragility of the heater matrix, avoiding the buildup of pressure due to coolant boiling is an important maintenance strategy in the Xantia.

[techbod]

yes I know what your saying but your missing one point and that's the thermostat so if you had too much antifreeze in it potentially wont operate as it should and that's when you get false problems, all im saying is don't over mix like many do as when its winter they don't flush the system and put new in they tend to keep adding to it

[Guest tomrostron]

thanks lads. tom

[cardsharc]

thanks lads. tom

TRY A PRESSURE TEST ON COOLANT SYSTEM MAYBE RAD IS LEAKING .SOMETIMES NOT ALWAYS NOTICEABLE WHEN ENGINE RUNNINNG

[rogermunns]

On several occasions, with various older cars, I've left the radiator pressure cap just loose. That is, in place but not making the pressure increase. That way water may not be lost.

This is just a trick to put off the evil day. And of course keep a close eye on the pressure gauge!

[zzf00l]

Hi.

Have experienced a split header tank in the past... quite common apparently. The seam half way down the tank is the culprit. Mine was on a V6 but I believe it is common on other models as well.

 

Ian

[C5-Nigel]

xantia rads have a nasty habit of springing a leak at the bottom on the passenger side this can often be mistaken for

aircon fluids dripping from the underside of the car. check for corrosion around this area white calcification with a little green

from the copper components leaking out.

Edited August 17, 2017 by C5-Nigel