Cooling system service refers to all aspects of repairing and maintaining vehicle cooling systems, including the replacement of old coolant with new. Like many services in the automotive aftermarket, there is more than one way to skin a cat. In this month’s article, we discuss several different methods of coolant replacement, how they differ from each other, the importance of cooling system service and some tips to ensuring that the coolant swap has been performed safely and efficiently.
The Importance of Cooling System Service
Vehicle manufacturers recommend coolant replacement at specified intervals. The intervals can be reduced if a car is driven under “severe” conditions, which can include stop and go driving, trailer towing and operation in extreme heat or cold.
Coolant, whether standard or long-life, consists of approximately 95% ethylene glycol and 5% additives. The additives include corrosion inhibitors, dyes, anti-foaming agents and lubricants. While the ethylene glycol will never wear out, the additives will. Additive wear out creates the need to change the coolant periodically.
Today’s engines run hotter than ever, with temps at or above 195° under load. Cooling systems need to dissipate more heat and do it with less coolant volume and smaller components than older systems. The radiators found in today’s vehicles feature smaller tubes and fluid passageways, making them more susceptible to clogging, which will also affect engine performance.
Any issues with system components or coolant quality can severely impact the overall performance of the vehicle. For instance, higher cooling system temperatures can also shorten the life of automatic transmission fluid (ATF). Heat degrades ATF. Most vehicles route ATF through a transmission cooler incorporated into the radiator. Higher cooling system temperatures prevent ATF from cooling properly, shortening service life and possibly leading to premature transmission failure.
There are several ways to swap old coolant for new coolant. The simplest way is the basic drain and fill. This method is typically performed by disconnecting the lower radiator hose and allowing the coolant to drain from the system using gravity. It requires no special equipment, but replaces only a limited amount of old coolant, which is typically confined to the coolant stored in the radiator. Often, a shop using this methodology will perform multiple cycles in order to achieve a higher exchange efficiency than can be achieved by a single pass, which can be time consuming.
Another means of coolant replacement is the coolant exchange method, which removes old coolant and adds new coolant via vacuum extraction/exchange. With this method, a coolant exchanger is connected to the vehicle via a radiator cap adapter and pulls out the coolant. While this method is more effective than the basic drain and fill and allows for a fast and simple service, it only replaces about 60% of the deteriorated coolant from the vehicle.
The most effective method of coolant replacement, achieving the highest exchange efficiency (often approaching 100% coolant replacement), is the true flushing/back-flushing method. This method requires two access points (usually through a disconnected upper radiator hose) and utilizes a pump to force new fluid through the cooling system, which displaces and forces the removal of old dirty coolant. This method allows for a forward flush or back-flush, depending on the method of vehicle connection used and the particulars of the system being serviced.
The VIPER approach to cooling system service is to incorporate a true flush methodology combined with an enhanced feature set to provide professional service operations a comprehensive service solution. Using the VIPER AF3250 Cooling System Service Center, most flushes are performed via an upper radiator hose connection (see photo above), using supplied adapters. This connection allows the machine to push new fluid into the vehicle using a pulsating action for improved effectiveness, going against the system flow and forcing the thermostat open. This back-flushing process results in enhanced cleaning action to break loose contaminants and scales in the cooling system. The used coolant is then captured as it comes out of the top of the radiator. Click here to view a video of the AF3250 in action.
Using this method, the entire service is performed while the vehicle is off to avoid the need for the tech to deal with a running, hot engine. The AF3250 uses an adjustable, shop air-operated pump to control the flow of coolant to and from the vehicle. The service requires no power supply (AC or DC), since it runs on shop air, and enables the operator to perform a pressure check to identify any system leaks and test the radiator cap function. Issues such as a defective radiator cap will not allow the cooling system to operate properly. Small leaks in hoses and pumps will lead to performance issues as coolant levels are reduced.
Unlike Automatic Transmission service, OEMs do recommend the use of chemical cleaner to remediate problem systems. Since cooling systems are not designed to experience high pressure, this is the most effective method to flush out systems with heavy sludge build-ups. Cleaners will break down accumulated sludge and debris, facilitating removal during the flushing process. It is critical that the cleaners used during this process are completely removed prior to putting the vehicle back into service. This is another big advantage of the true flushing method, because the greater exchange efficiency achieved by this method ensures removal of the cleaning solution during the flushing process.
When in the market for a cooling system service machine, shop around and make sure the machine purchased will meet your specific service needs. As more long-life coolant equipped vehicles are finding their way into the aftermarket service facilities, be prepared to meet the service need. Flushing solutions/cleaners, coolant replacement options and trained technicians are all essential to providing the best service possible.
Due to the year round usage and high demand for service offered by this type of product, we recommend that you not make your decision based on the selling price only. Make sure your decision is based on ease of service, amount of training required to properly operate the equipment, assurance that you can service all of your customers’ vehicles and that the service offered by the equipment (and it’s approach to coolant replacement) is consistent with your service menu and operating philosophy.