The reason we need to take care of this system is that it is used for removing excess heat from the engine, to keep the engine operating at its most efficient temperature, and to get the engine up to the correct temperature as soon as possible after starting. Ideally, the cooling system keeps the engine running at its most efficient temperature no matter what the operating conditions are.
Liquid cooled engines have passages for the liquid, or coolant, through the cylinder block and head. The coolant has to have indirect contact with such engine parts as the combustion chamber, the cylinder walls, and the valve seats and guides. Running through the passages in the engine heats the coolant (it absorbs the heat from the engine parts), and going through the radiator cools it. After getting "cool" again in the radiator, the coolant comes back through the engine. This business continues as long as the engine is running, with the coolant absorbing and removing the engine's heat, and the radiator cooling the coolant.
If we are not sure slow leaks including at hoses, seals, or a heater core, a cooling system pressure tester can be used to check the pressure in the cooling system. Because of this tester, the leak can then be found and fixed before it causes a major problem. You can test your cooling system at your Citroen Dealer, Yontrakit, they have it. However, they usually use this tester to check slow leaks at heater core before you can notice from the wet carpet. Unfortunately, they can not check the radiator cap fuction.
1.the engine's water jacket
2.thermostat
3.thermostat cover
4.water pump
5.radiator
6.radiator cap
7.expansion tank
8.electronic cooling fan
9.water hoses
10.heater core
11.temperature sending units
Actually it is manufactured in one piece with the water jackets cast into the block and cylinder head. At normal operating temperature, the water pump forces the coolant through the head gasket openings and on into the water jackets in the cylinder head. It flows around in there, cooling everything off by absorbing the heat. After doing its thing, the coolant flows through the upper hose to the radiator where it releases the heat. Then, the water pump sends it back down into the engine's water jackets to continue the cooling process.
Unchanged coolant may cause damage to your water jackets and other parts in the cooling system. (see related story on Coolant (Thai Version))
The thermostat provides control for your engine's warm-up period. The thermostat is located between the engine and the radiator. This little temperature-sensitive spring valve stays closed during engine warm-up. When the thermostat is closed, it prevents coolant from leaving the engine and circulating through the radiator until the correct running temperature is reached. when the right temperature is reached, the spring valve opens, allowing coolant to circulate through the radiator to be cooled.
For Xantia, the thermostat cover is making of some kind of plastic or ABS type plastic (I am not sure). It is cover your thermostat and there also have rubber gasket covering the thermostat to make sure that there is any coolant leaks from the cover.
Moreover, thermostat cover and cap should be taken care. Buying extra cover cap in your car is recommended at only Baht 15. If not, it may broken without prior notice and may cause you more or at least overheating.
Water pumps forces the coolant through the engine block. Many water pumps have a spring-loaded seal to avoid leakage of water around the pump shaft. Modern pumps are fitted with pre-packed ball bearings, which are sealed at each end to eliminate the need for lubrication. Any leaks from water pump indicated the damage. It needed to be replaced.
The radiator is a device designed to dissipate the heat which the coolant has absorbed from the engine. It is constructed to hold a large amount of water in tubes or passages which provide a large area in contact with the atmosphere. It usually consists of a radiator core, with its water-carrying tubes and large cooling area, which are connected to a receiving tank (end cap) at the top and to a dispensing tank at the bottom. Side flow radiators have their "endcaps" on the sides, which allows a lower hood line.
Sooner or later, almost everyone has to deal with an overheating car. Since water is readily available, it is not beyond the ability of most people to add some to their radiator if it's low.
First, turn off the A/C. If the car is not seriously overheating, this will reduce the engine's temperature. The AC evaporator is located in front of the radiator, and it adds heat to the air going to your engine. The hotter the incoming air is, the less efficient the radiator will be.
Second, turn on your heater (set on highest temperature setting, with blower on highest setting). This will be uncomfortable for you, but it will cool the engine by transferring the heat to the air. Roll down the windows, and remember how 'hot' you'll get if your engine needs replacement!
If you're stuck in traffic, pull over and stop. Unless you're moving, very little cool air reaches the radiator. Open the hood and let the engine cool off. This takes time, so be patient. Use the time to go get a jug of water (not necessary coolant because it is usually something wrong with your car that you need to recheck and change the coolant again).
Check the pressure of the system by wrapping a cloth around the upper radiator hose and squeezing it. Before doing this, place a large cloth over the radiator cap, and CAREFULLY release the pressure.DANGER: SERIOUS BURNS CAN RESULT FROM THE HOT COOLANT. IF IN DOUBT, WAIT UNTIL THE ENGINE COOLS COMPLETELY. In most car, running the engine while opening the cap can help you open it more easily when it heat (less danger). Unfortunately, I never try with my Citroen but can be used with other open cooling system.
If the coolant is low, start the engine, and slowly add the water or coolant necessary to fill it up.
THE ENGINE MUST BE RUNNING. ADDING COOLANT TO A WARM ENGINE CAN CRACK THE BLOCK. By running the engine, the coolant keeps moving and reduces the chances of this type of damage occurring.
6.Radiator Cap (Pressure Cap)
The radiator cap acts as more than just a "lid" for your radiator; it keeps your engine cool by sealing and pressurizing the coolant inside it.
What makes the radiator cap special is that it is designed to hold the coolant in your radiator under a predetermined amount of pressure. If the coolant was not kept under pressure, it would start to boil, and soon you would have boiled all of your coolant away.
However, the radiator (or pressure) cap prevents this from happening by exerting enough pressure to keep the coolant from boiling. If the pressure is increased, the boiling temperature is also increased. (see related story: coolant) Since the boiling point goes up when the pressure goes up, the coolant can be safely heated to a maximum spec of heating temperature without boiling.
What makes this important is that the higher the temperature of the coolant is, the greater the temperature gap between it and the air temperature is. This is the principle that causes the cooling system to work; the hotter the coolant is, the faster the heat in it moves to the radiator and the air passing by. So, a cooling system under pressure takes heat away from the engine faster, which makes it more efficient.
If your cooling system is under too much pressure, it can "blow its top!" To prevent this, the radiator cap has a pressure relief valve. The valve has a preset rating that allows it to take just up to a certain amount of pressure. When you turn the cap on the filler neck of the radiator, you seal the upper and lower sealing surfaces of the filler neck. The pressure relief valve spring is compressed against the lower seal when you lock the cap. Important!! Xantia cap is difficult to fit in place. Please be careful when you close the cap and make sure that it is tight and secure. If you make it right, you will feel like turning plastic through rubber seal.
Watch out! You can only fill up your coolant at maximum level indicated in your expansion tank. Do not fill it up to the top.
7.Expansion Tank
Most Citroen?s cooling system have expansion tank (not in some BX model), not like open system as Japanese cars. It is not overflow tank but it is part of your cooling system. You need to check your coolant level in here.
When the engine reaching running temperature, the coolant will be full in this tank and reduced to the appropriate coolant level when it is cool. So, once again, do not fill up coolant full (please check the appropriate level of fill up). This way, no coolant is lost if the system is functioning properly. But if you fill up too much coolant, it will overflow out of your cap. That is fine.
Another function of the expansion tank is to remove air bubbles from the cooling system. Coolant without air-bubbles is much more efficient than coolant with air bubbles, because it absorbs heat much faster.
The advantage of the expansion tank is that while the level of coolant contained in it rises and falls, the radiator is always full. Remember!! Citroen car need to release the air-bubbles release cap while you fill up coolant after taken off any parts of cooling system or no coolant left in your expansion tank before fill up. If it is only top up, no necessary to release the air-bubbles release cap.
8.Cooling Fans
The reason the coolant goes into the radiator is to allow air to pass through it and cool the coolant. When you are driving fast enough, the air rushes through the grille of the car and passes through the radiator core. If you aren't driving fast enough to push air through the radiator, then the fan will pull the air through.
The fan improves cooling when you are driving at slow speeds, or if the engine is idling. Citroen cars newer than DS (engine mounted fan) and GS (air cool) models use electric fans to cool the engine. The radiator is located in the usual place, but an electric motor drives the fan in front of the radiator. A thermostatic switch is used to turn the fan on and off at predetermined temperature settings, which it senses. Except cars that have air conditioning that by pass the thermostatic switch that make the fans run continuously at low speed. Citroen has two electric fans that work the same time and speed (not independently)
The exception to this for Xantia that equipped with air conditioning system. If you turn on the air conditioner, you activates the air conditioning control unit on. This unit bypass the pre-determine temperature thermostatic switch, and the fan will run at low speed until the pressure switch, located at the top of the evaporator, order the fan to run. When pre-determine pressure of R134a reach the hi-limit, the control unit will order the fan to run at high speed to make sure that your air conditioning is cool enough. (see related story in Thai version of Xantia Air-Conditioning system topic). If this unit works improperly or you turn off the air conditioner, the thermostatic switch is re-activated, and goes back to turning the fan on and off, according to its instructions. At least, your car will not overheating but air-conditioning is not cool enough (may be because of low level of 134a)
9.Radiator Hoses
Hoses are used to connect the engine and the water pump to the radiator. Radiator hoses are made of flexible rubber; size varies depending upon the type of engine. Smaller hoses run to the heater core, these are known as (you guessed it) heater hoses. It is easy to damage at the pipe-end that made by plastic and it is very expensive. Sometime, it is OK. but rubber seal is leak. Please check for any leaks.
Three types of hoses are; the common hose, the molded or shaped hose, and the accordion type hose. All of these hoses may have spiral wire in their construction. Spiral wire can be molded or inserted into the hoses, in the required shape, when the hose is constructed.
The common hose is straight and cannot take much bending before collapsing. It is made of rubber with fabric reinforcement.
Molded or shaped hoses are the same as the common hose with one exception. They will not collapse when bent, because all of the bends that they need are already molded into them.
Accordion type hoses not only put up with all kinds of severe bending, but they also absorb some of the vibration between the engine and the radiator.
The heater core is a smaller version of the radiator that is used to keep your toes warm when it's cold outside. For Xantia and XM use the heater core to warm the air coming from the air conditioner if the dash setting is not on "cold" (coldest level. The good point of doing this is to maintain the temperature inside your car at the level you set. Not too cold when the compressor is running and too hot when compressor is cut-off.
The air-conditioning compressor is running most of the time while you turn the AC switch on. It will cutting off only when 134a pressure reaches the minimum limit that determine by pressure switch.
The heater core is mounted under the dash board behind the cooling core. Some of the hot coolant is routed through this little radiator, by more hoses. A small electric fan (the same fan for cooling core) is also mounted there especially for the purpose of directing the heat inside the car. To turn this fan on, you use a switch called "fan" or "blower," located on your control panel. The principle is exactly the same as the one used in the radiator for your engine, except that the heat is released inside the car instead of outside. Most engines use the heater core to warm the air coming from the air conditioner if the dash setting is not on "cold". If your car is running hot, turning the heater on will help to reduce the heat in the engine. Unfortunately, most cars don't overheat when the weather outside is cold.
Since it is critical for you to keep an eye on the temperature of the coolant in your cooling system at all times, your car will have either a gauge or a warning light located on the instrument panel or dashboard. The question is, how does the information about your coolant get to the gauge? It gets there, or is sent by the temperature sending unit.
The temperature sending unit is a device that is placed so that it can determine the temperature of the engine coolant. Simply put, its resistance to electricity changes with increases and decreases in the temperature of the coolant. The electric resistance changes control the movement of the indicator needle on the temperature gauge. In some model such as some CX and some BX, you have an indicator light, or lights, these changes will cause the bulb to be connected to the battery if the temperature of your coolant gets too high. If this happens, the light goes on with the ?STOP? warning light.
Please STOP!!!
1.Why my coolant is gone so quickly without any noticeable leaks?
ANS. the coolant may leaks through Heater Core. If it is just and only slow leak, you need to check by using tester at Citroen dealer. But you can check yourself first, if the carpet on the left-front seat is soak or wet, the heater core is leaking. Renew!
But if you can not find any leaks, check your radiator cap and make sure that it is tightly secured.
Furthermore, if you can find coolant leaking under the expansion tank but can not find where is it leaking from after stop the engine for 5-10 minutes. Please change your radiator cap. It can not contain upper pressure limit. Usually, when we stop the engine for a while, the heat accumulated more in the system. ( this can be use with other Citroen Model, sometime you can heard the noise of boiling water from the expansion tank)
2. What is the normal temperature of my car?
ANS. If it is Xantia. the answer is between 80-100 degrees when you turn off air-conditioning. But if your 134a charged with appropriate level, the engine should run at around 80-90 depending on external temperature and traffic condition. More traffic and hot external temp.will make your engine temp. lower to 80-90 degrees. For model without temp. guage, don't worry. notice the warning light.
3. What happen if I turn on air-conditioning but engine temp. still exceed 90 degrees?
ANS. I suspect that you need to charge more 134a. Not enough 134a will make your electric fan delay on working at high speed. If you still can not solve the problem, please check your electric fan speed or mulfunction.
4.Why my engine temp. running below 80 degrees?
ANS. May be you charge too much 134a or use the wrong R12.
5. My radiator is leaking, what can I do?
ANS. You must change the new one. But if you live in some other countries such as USA, you can probably buy the plastic and alluminum radiator repair kits to repair them. In Thailand, you can find from Citroen Auto part shop or replace with tailor-made copper radiator. Baht 3.5-4.0 thousands compared to the original part of around Baht 10 thousands. Definitely, copper radiator can be repaird if leaking in the future.