Aluminum is rapidly becoming the material of choice for almost all cooling system applications, and aluminum cooling systems are now part of almost every new vehicle manufactured around the world.

SYSTEM MAINTENANCE

The failure to properly maintain an aluminum system can lead to premature, sometimes catastrophic failures of the radiator and/or heater core. This information is written in order to help you understand 2 vital factors in the proper operation of your vehicle's cooling system.

1. Proper maintenance of an aluminum system.

2. Understanding how your cooling system  professional recognizes and diagnoses the symptoms of aluminum system failure.

The majority of aluminum cooling systems have been designed to operate utilizing organic coolants. These extended-life coolants are less toxic to humans than their ethylene or propylene glycol brethren, but their extended (5/150) life span allows for you, the consumer, to ignore their cooling system for an extended period of time. This is where the cooling system professional comes into play. As the consumer, NARSA feels very strongly that you must be educated as to the importance of properly maintaining the aluminum system in your vehicle. It is not good practice to wait the full 5/150 life of the coolant. Rather, NARSA recommends that you should have the system checked every 2 years or 24,000 miles and serviced within the time frame of the coolant life if no adverse conditions present themselves earlier. In addition, anti-freeze containing carboxyiate or similar organic acid technology (OAT) cannot be mixed with conventional anti-freeze (ethylene or propylene glycol based).

The OAT anti-freeze is designed specifically for the protection of the aluminum system. It provides a microscopic carrier, a thin gaseous film, as protection for the system components. The film "bonds" to the aluminum surfaces it conies in contact with, providing protection against corrosion. When conventional anti-freeze is introduced into the system, this protection is washed away and chemical reaction corrosion begins almost immediately. Remember that the use of long life anti-freeze as a replacement for conventional anti-freeze does not extend the recommended system requirements as set for the by the manufacturer. The "extended" life or protection ability of the long life coolants only applies to new vehicles in which the coolant is installed initially and then maintained by regular system service.

THE RIGHT COOLANT

Coolant conditions (level and color) are first checks. Just because it's orange doesn't mean it's clean. Vehicles using organic technology coolant must not be allowed to operate with low coolant levels. Proper coolant levels are vital to aluminum systems to provide cleaning abilities. Low coolant levels may allow suspended contaminants to drop out of solution and clog the system causing overheating.

Your cooling system specialist will first check the solution with an anti-freeze tester for proper freeze-up, boil-over protection. Many major automobile manufacturers now recommend the use of a refractometer when testing anti-freeze. The use of this tool presents the technician with a more complete picture of the coolant's condition.

Next, the cooling system technician will check the pH level. Any reading between 7.7 and 9.3 total pH is within manufacturer's guidelines and is therefore acceptable.

The technician will then check the system for electrolysis (stray electrical current within the cooling system) using a multi-meter. Any reading over .1 volts indicates excessive voltage in the system. The system will be checked with the engine off and then again when starting and running the engine. Many electrolysis failures are caused by poor starter grounds, so it is important for the technician to turn the engine over at least once during this test.

TWO YEAR VS. FIVE YEAR

If the coolant solution fails any of the tests or you have any suspicions regarding its quality, the cooling system specialist will recommend a complete flush and fill. When the flushing is complete, the system should be refilled using the manufacturer's recommended anti-freeze. NEVER re-use old anti-freeze, regardless of its condition or color.

Bear in mind that conventional anti-freeze chemistry (ethylene or propylene glycol) will override OAT (Organic Acid Technology) anti­freeze chemistry, converting the system from a five-year service cycle to a two-year cycle. In addition, the same is true for systems containing OAT technology coolant that have been topped up using conventional coolant(s). The coolant solution for your vehicle will be created by making a 50/50 mix of anti-freeze and water. A 65% anti-freeze to water ratio should not be exceeded as this may cause silicates and/or additives to drop out of solution, clogging the system that was just cleaned. Once the system is filled, the technician will start the engine and run it up to operating temperature making sure that any excess air escapes the system. The system should be allowed to cool and then it should be checked for proper coolant level and any leaks.

What do you do when you are faced with a suspected or obvious cooling system problem or failure? The first and most important step is to have your cooling system professional perform a complete diagnosis of the problem. He should talk with you and obtain as much information about the trouble, when it started, your driving style and habits and any other pertinent information. You should know if this is the original coolant or whether it's been replaced. What is the condition of the coolant? The technician should check the pH level, check for electrolysis, and look for residue around the filler neck. What is the color of the coolant? Performing a complete system inspection will allow the technician to get to the heart of the problem, correcting the cause and not just curing the symptom and preventing a possible comeback.

The major causes of failures in aluminum systems are abuse and neglect and electrolysis/pH problems. Once the cooling system technician has located the failed part and determined the cause(s) of the failure, there are several steps he must take first before replacing the failed part.

In order to avoid problems relating to abuse or neglect (both of which will most likely provide your vehicle with electrolysis/pH problems), you must understand the importance of proper maintenance of your vehicle's cooling system. If the problem was a pH problem, your cooling system professional must find the cause of the imbalance in the solution. Has the system been topped off or refilled with bad coolant? Your technician will ask you the last time the system was serviced and by whom.

ACID OR ALKALI

Incorrect pH levels (too acidic or too alkali) will accelerate cooling system corrosion. Aluminum components will pit and flake. These flakes will then enter the coolant solution, remaining in suspension until they reach a "cooler" area (like the bottom of a radiator or heater core) where they will drop out of solution and build up until the system is clogged. This phenomenon is known as transport depositing and is deadly to an aluminum system.

ELECTROLYSIS

If electrolysis is the problem, it must be corrected before any replacement parts are installed. If there is excess voltage in the system, the coolant becomes an electrolyte and galvanic action occurs leading to premature failure. The aluminum component, which comes in contact with the charged coolant, will be oxidized and coolant loss will eventually result when the material is sufficiently corroded.

The most common form of corrosion failure is the formation of pinholes in the inlet or outlet tanks or connections of aluminum radiators. In addition, electrolysis will alter pH levels, accelerating corrosion. If electrolysis is detected and confirmed, the source of the excess voltage must be located and corrected. The starter, alternator and radiator cooling fan(s) are prime candidates for producing stray electrical charge due to missing or inadequate grounds. But if the suspect is a different component or accessory the problem circuit(s) will have to be isolated.

Many newer systems have flow restrictors to limit the speed at which the coolant moves through the system. This is done for two reasons. The first is to allow more complete hear transfer from the components to the coolant. The second is to protect the thin gaseous film mentioned earlier. It can be washed away due to acceleration of the coolant moving through the system. In addition debris or other contaminates in the system can also "brush” away this protective layer. This is why cooling system maintenance, especially for aluminum systems, must be performed on a regular basis.