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The Automobile Cooling System and the
Mityvac® 04520 Cooling System Test Kit
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Please use caution: Do not attempt this method on a hot vehicle. Never attempt to remove a radiator cap on a hot vehicle. Personal Injury could result.
Note: The information contained in this article describes only general procedures used in testing a cooling system on a typical automobile. For vehicle specific procedures, it is recommended to purchase and use the repair guide for your vehicle. |
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As a general rule, the cooling system on an average vehicle can malfunction at any time but will usually experience problems during seasonal weather changes. These problems often occur due to the effect that temperature and barometric pressure changes have on the hoses and seals in the system. Most repair shops and manufacturers recommend having the cooling system checked in early fall and late spring (if you enjoy such seasonal changes). Otherwise, you should check the cooling system once a year by performing a visual inspection of all hoses, the water-pump area (if visible) and then check to see if there are any "trails" that may indicate a leak has occurred. The "trails" are normally rust, green or orange in color (depending on the coolant type used). These "trails" will stream down from where a leak is present. Some leaks will only occur when a system has been running for a while and is up to full operating temperature. Other leaks only appear after a system has
been shut down and has cooled off. For these reasons it is important to check the system in both conditions.
Q: Do all vehicles have cooling systems? Why does a vehicle need a cooling system?
A: Yes, all vehicles have a cooling system. An engine needs some method of removing the excessive heat that is built up during the combustion process that occurs within the engines cylinders. The excessive heat is usually removed in one of two ways: air circulation around the engine cylinders or a water/coolant mixture circulating around the cylinders inside of an engine block. For the purpose of this article, I will only discuss a liquid filled engine cooling system.
Q: What are the parts of a cooling system?
A: The basic engine cooling system consists of the radiator, cooling fan(s), fan clutch (if equipped), fan belt (if equipped), water pump, engine block and heads, gaskets, thermostat, hoses and the heater core.
Q: How does a cooling system function?
A: The cooling system functions by removing excessive heat from a running engine using a radiator and a series of hoses that hold and circulate coolant at a constant rate. This circulation of coolant prevents excessive temperatures that can damage the engine.
Q: What tests can be performed on an engine’s cooling system?
A: This is a broad question because there are several tests. I will explain:
1. Pressure Test: This test requires applying pressure using a tool such as the Mityvac“ 04520 Cooling System Pressure Test Kit. This test simulates the running condition of the entire cooling system by placing pressure on the hoses, seals and gaskets throughout the system.
2. Temperature Test: This test is a critical test that is performed to measure the "live" system temperature. It will indicate if the engine is running too cold or too hot. By using the temperature probe that is provided with the Mityvac“ 04520 Cooling System Pressure Test Kit, the actual operation of the cooling system thermostat can be monitored as it opens and closes to regulate the fluid flow through the cooling system. Most manufacturers and parts suppliers have published data on what the correct thermostat temperature should be for you vehicle. It is not recommended to use a "hotter" or "colder" thermostat than the manufacturer recommends because the vehicle’s onboard computer monitors the engine temperature very closely to ensure the best possible fuel mixture is maintained.
3. Coolant Concentration Tests: This test is performed several ways using a hydrometer, a refractometer or alkaline test strips (the hydrometer is most common). Any one of these tests will indicate if you have the correct balance of water and coolant in the system. The mixture in most cases should be 50/50 water/coolant. Some manufacturers recommend a 40/60 water coolant mixture. As a general rule, never run 100% coolant, as coolant by itself cannot dissipate heat quickly enough. 100% water will create problems with corrosion along with poor heat dissipation.
4. Pressure Cap Tests: There are two basic cap tests that can be performed which are the pressure and vacuum test. The pressure test will indicate at what point the cap will yield under pressure (this is usually printed on the cap). This test can be performed using a dedicated cap adapter in conjunction with the Mityvac“ 04520 Cooling System Pressure Test Kit.
The vacuum test is still somewhat of a new test for most technicians and is often overlooked. Older vehicles used a cooling system known as an "open system" that purged coolant as it expanded from the heat. As environmental laws changed, vehicles were required to have a coolant recovery system. Newer vehicles have what is known today as a "closed system" that captures excess coolant and then draws it back into the system for use again. A vacuum test of the cooling system cap is needed on today’s vehicles because the cooling system is a closed system and it must have the ability to recover coolant from an overflow tank or an expansion tank. This coolant recovery occurs as the system cools down and creates a vacuum effect. This is due to the contraction of the cooling liquid within the closed system. As a general rule of physics, liquids expand with heat and contract when cooled; this is a constant phenomenon within the cooling system of today’s automobile.
Also note that a pressure cap can pass one test but fail the other, it is good practice to check both operations when testing the pressure cap.
Q. Is it okay to use "stop leak" in a cooling system.
A: A "stop leak" material is usually considered a temporary fix to a permanent problem that exists. These types of additives are normally used in an emergency situation, to get you home or to a repair shop. Using these types of additives in a cooling system will generally plug up more than the leak you might be experiencing. It will block up passages in the radiator and cylinder heads and reduce the cooling efficiency of the system. Most repair facilities and manufacturers do not recommend using a "stop leak". If you do have an incident where this material was put into a cooling system, the system would first need to be repaired and then would require flushing to prevent any further complications such as overheating.
Q: How often should the coolant in a system be changed?
A: Most manufacturers recommend changing coolant about every 30,000 miles. If you have an extended life coolant, then the change interval would go as high as 50,000 miles. If you go beyond these guidelines, then the properties of the coolant begin to deteriorate dramatically. Corrosion and electrolysis will begin to destroy the system internally. |
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