Part 6: Cooling Systems

The cooling system removes the tremendous heat generated by your vehicle’s engine. This heat, if left uncontrolled, can quickly damage vital engine components. The cooling system is sealed and under pressure. 
Good practice is to have the car cooling system checked yearly. Failure to maintain the cooling system can result in overheating, which can cause severe damage to the engine. 
In the US, The National Automotive Radiator Service Association (NARSA) recommends that motorists follow the seven-point preventative cooling system maintenance check, listed below, which is designed to identify any areas that need attention. 
7 Point Preventative Cooling Maintenance Check
1. A visual inspection of all cooling system components, including belts and hoses. 
2. A radiator pressure cap test to check for the recommended system pressure level. 
3.  A thermostat check for proper opening and closing. 
4. A pressure test to identify any external leaks to the cooling system parts; including the radiator, water pump, engine coolant passages, radiator and heater hoses, and heater core. 
5. An internal leak test to check for combustion gas leakage into the cooling system. 
6.  An engine fan test for proper operation. 
7. A system power flush and refill with car manufacturer’s recommended concentration of coolant 
 
Let’s take a closer look at each of these checks. 
6.1 Visual Inspection 
Hoses  
 
What you are looking for is the condition of the belts and hoses. The radiator hoses and heater hoses are easily inspected just by opening the bonnet and looking. Ensure that the hoses have no cracking or splitting and that there is no bulging or swelling at the ends. If there is any sign of problems, the hose should be replaced with the correct part number for the year, make, and model of the vehicle. You can use our VIN lookup or Make Model Year Search on Start My Car to find the correct hose for your vehicle. Never use a universal Radiator hose unless it is an emergency and a proper moulded hose is not available.
Heater hoses are usually straight runs and are not molded, so a universal hose may be used and often is all that is available. Also ensure to use the proper inside diameter for the hose being replaced. For either the radiator hoses or the heater hoses, make sure that you route the replacement hose in the same way that the original hose was running. Position the hose away from any obstruction that can possibly damage it and always use new hose clamps. After you refill the cooling system with coolant, do a pressure test to make sure that there are no leaks.
Belts

 

On most older vehicles, the water pump is driven by a V-belt or serpentine belt on the front of the engine that is also responsible for driving the alternator, power steering pump and air conditioner compressor. These types of belts are easy to inspect and replace if they are worn. 

 

The backside of the serpentine drive belt, or the smooth side, usually drives the water pump. If the serpentine belt gets oil soaked or glazed, it will slip and not provide the proper circulation to keep the engine cool. And if there is oil on the serpentine belt, it’s coming from somewhere so you will need to find out where and fix it before putting on a new serpentine drive belt. 

 

Look for tears or abrasions. If you see any it means the serpentine drive belt is rubbing a pulley flange or bolt as it winds it way around. This will happen more often as the drive belt gets older. Also look for pinholes and/or bumps. If you see any it means dirt and debris is getting in between the serpentine drive belt and the pulleys. Turn the belt around and see if there are chunks of the ribs missing. 

 

Lastly, look for dry cracking on the inside of the belt. Hairline cracks are normal, but if they go into the backing, or flat side, of the serpentine drive belt you will need to replace it. 

 

A good rule of thumb for serpentine drive belts is that if cracks are observed 3 mm apart, all around the belt, the belt may be reaching the end of its serviceable life and should be considered a candidate for changing. 

 

If your car is relatively new, the water pump will probably be driven by the timing belt. This belt usually has a specific life expectancy at which time it must be replaced to ensure that it does not fail. Check your manufacturer’s handbook to see the correct replacement intervals. Since the timing belt is inside the engine and will require partial engine disassembly to inspect, the labour to replace this belt can be significant and it is a good idea to replace the water pump at the same time that the belt is replaced.  

 

6.2 Radiator pressure cap test

A radiator pressure cap is designed to maintain pressure in the cooling system at a certain maximum pressure. If the cooling system exceeds that pressure, a valve in the cap opens to bleed the excessive pressure into the reserve tank. Once the engine has cooled off, a negative pressure begins to develop in the cooling system. When this happens, a second valve in the cap allows the coolant to be siphoned back into the radiator from the reserve tank. If the cap should fail, the engine can easily overheat. 

 

A pressure test of the radiator cap is a quick way to tell if the cap is doing its job. It should be able to hold its rated pressure for two minutes. Since radiator caps are quite inexpensive, NARSA recommend replacing it every 3 years or 60,000 kilometers. Make absolutely sure that you replace it with one that is designed for your vehicle. One again, check Start My Car for your vehicle specific radiator cap. 

 

6.3 Thermostat check for proper opening and closing 

This step is only necessary if you are having problems with the cooling system. A thermostat is designed to open at a certain coolant temperature. 

 

To test a thermostat while it is still in the engine, start the engine and let it come to normal operating temperature (do not let it overheat). If it takes an unusually long time for the engine to warm up or for the heater to begin delivering hot air, the thermostat may be stuck in the open position. If the engine does warm up, shut it off and look for the two radiator hoses. These are the two large hoses that go from the engine to the radiator. 

 

Feel them carefully (they could be very hot). If one hose is hot and the other is cold, the thermostat may be stuck closed.If you are having problems and suspect the thermostat, remove it and place it in a pot of water. Bring the water to a boil and watch the thermostat. You should see it open when the water reaches a boil. Most thermostats open at about 90 degrees Celsius. An oven thermometer in the water should confirm that the thermostat is working properly. 

 

Visit Start My Car to find the replacement thermostat for your vehicle. 

 

6.4 Pressure test to identify any external leaks 

Pressure testing the cooling system is a simple process to determine where a leak is located. To perform this test, you will need to invest in a pressure tester, available right here on Start My Car.This test is only performed after the cooling system has cooled sufficiently to allow you to safely remove the pressure cap. Once you are sure that the cooling system is full of coolant, a cooling system pressure tester is attached in place of the radiator cap. 

 

The tester is than pumped to build up pressure in the system. There is a gauge on the tester indicating how much pressure is being pumped. You should pump it to the pressure indicated on the pressure cap or to manufacturer’s specs. 

 

Once pressure is applied, you can begin to look for leaks. Also watch the gauge on the tester to see if it loses pressure. A loss of pressure is indicative of a leak somewhere.Most leaks should be visible from either underneath and above the engine. 

 

The most notable exception is a leak in the heater core, since the core is enclosed and not visible without major disassembly. One sure sign the heater core is leaking is the unmistakable odour of antifreeze inside the car. You may also notice the windshield steaming up with an oily residue.To be continued in next week’s edition. 

 

Summary 

As I have mentioned often in this series, none of the components which make up the cooling system are particularly expensive to replace, relative to the cost of having to fix an engine which has overheated. It is therefore well worth taking the time to inspect your cooling system and nip any potential problems in the bud.