Radiator TLC

Cooling efficiency will drop fast when corrosion blocks a radiator’s tubes.

With aerodynamic styling and hotter-running engines, radiators have to work even harder.

The radiator in today’s truck needs to throw off more heat while occupying less space, resulting in designs that cram more cooling surface into a smaller space and have thinner metal sections. Since these thin sections can be vulnerable to corrosion on both sides, maintenance is more important than ever.

We visited Mike and Daughter Radiator Aid in Lancaster, Pa., to get the low down on just what destroys radiators, what keeps them together and what you should keep in mind when needing a repair. Mike Mascuch started the business in 1960 and eventually sold it to his daughter Shawn Marie Sholly, who is president. Her husband Tom Sholly is vice president.

The business purchases its quality replacement cores and radiators from Proliance and another manufacturer, and Proliance helped us arrange for our visit.

Shawn Sholly told us preventive maintenance can make a big difference in the life of your radiator. She says, “If more people did more preventive maintenance, I’d have fewer radiators to repair.”

How radiators work
Radiator is a misnomer – the unit radiates very little heat. The unit’s purpose is to provide a very large surface to heat the outside air, an ideal means of getting rid of the heat in the coolant.

The radiator has top and bottom header tanks that collect and guide the coolant to and from the engine. The tanks are connected by dozens of very thin metal tubes that are flat on the sides to maximize the number of tubes and amount of surface that can be fitted into a small space. The use of these thin, narrow coolant passages ensures the liquid will flow through the tubes rapidly, rather than becoming stagnant. This increases the unit’s ability to get rid of heat, but makes radiators subject to internal clogging if you don’t keep your coolant in top condition.

Once the thermostat opens, the coolant passes down through the tubes, dropping its temperature 20 degrees or more even on the hottest days – if the radiator is clean both inside and out.

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The tubes are linked with hundreds of closely spaced flat metal fins. The fins don’t contain any liquid, but because metal carries heat very effectively and no part of any fin is more than a half-inch from a tube, they get almost as hot as they would be if they were filled with coolant. The result is a lot of hot square footage. A radiator with just 200 fins 20 inches long and 5 inches wide would have 250 square feet of surface to heat air, and that doesn’t even count the coolant tubes themselves.

The rub is that those closely spaced fins catch dirt. They are only .003 inch thick these days, Mascuch says. That’s so thin that fatigue combined with high-speed wind can actually bend them.

So, Masuch told us, it’s really important to keep the radiator clean, both inside and out. Outside cleaning must remove not only road salt, which will corrode the radiator, but non-corrosive dirt that would reduce cooling efficiency. Dirt not only blocks the flow of heat from metal to air, but reduces the amount of air passing through. Air is the only place the heat has to go.

Cooling problems always snowball and attack the radiator. Anything that interferes with the radiator’s ability to get rid of heat increases the operating temperature and pressure in the system. The higher temperature and pressure then accelerate corrosion and physical stress, which work together to create radiator leaks.

External cleaning
An important first step in radiator maintenance is regular cleaning of the outside when you drive on snow-covered roads. The salt and calcium chloride used to melt ice and snow will attack the thin metal fins on radiators, just as it attacks the rest of the truck chassis.

“Flush road salt off,” Sholly says. “The longer you leave it on, the more cores we get to replace.”

Mascuch says it’s best to flush off the stuff by the next day, if you can. Don’t just use a garden hose. Use a pressure washing process that produces hot water and controlled pressure, like what’s available at many truckstops. (Too much pressure can bend the thin metal fins.) Open the hood and go in between the charge air cooler and radiator to gain access to the front of the radiator.

“Road salt and sludge deteriorate the fins,” Mascuch says. “The temperature will go up first as the fins get corroded off. The A/C may stop performing well. Eventually, the pressure will go up and the radiator will start leaking.”

Salt corrosion also “kills the bolts that hold the tanks on,” says Mascuch. There may be 20 or more bolts holding them at top and bottom. When a repair becomes necessary, it helps if all the bolts come out easily. If they are corroded, they’ll break off, making the job much more difficult and expensive.

Even non-corrosive dust and dirt should be flushed off before it accumulates and interferes with heat flow. You should also look at the fins every few months. Where they are bent, straighten them to allow more airflow. There is a special tool called a fin comb that may help.

You can also check that your radiator mounting bolts remain tight. Look at any rubber mounting bushings used and replace them if they have been crushed by vibration and no longer keep the radiator snugly mounted. Still Mascuch says most radiator failures don’t happen because of the mounting system, but because of corrosion.

Coolant maintenance
The next step is to maintain your antifreeze.

“Mixing antifreeze is a problem,” Sholly says. “You just can’t mix the different types. Corrosion often occurs from the inside out. This happens because of neglect of the antifreeze. Take care of the coolant!”

There are two ways of doing this. You can use ELC (“Extended Life Coolant”) and add only ELC when you have leakage or evaporation, plus adding a bottle of extender in the middle of each change cycle. Or you can use more traditional methods.

The best of the traditional methods is the use of only Fully-Formulated TMC RP-329 Type A coolant – you’ll see this designation on the jug. It contains full cooling system protection. Combine this with some sort of coolant filter that provides a controlled release of SCAs, or “Supplemental Coolant Additives.” The best ones actually adjust the rate at which they add SCAs to the conditioners. The SCAs are necessary to keep system protection topped off as the anti-corrosive chemicals in the original antifreeze wear out. You need to test for SCAs at your routine maintenance intervals with this type of protection. But if you use only the Fully-Formulated coolant and the right SCA-adding filter, you’re likely not to need to add SCAs.

Either of these systems will extend coolant life to at least 600,000 miles with full protection if you follow the rules for your method. Keeping the right antifreeze with you in the truck and adding only that is the most important key to making either system work.

You also need to worry about the concentration of the coolant. Make sure to keep the antifreeze at a 50/50 concentration unless you live in an extreme northern climate, where 40/60 is allowed. The best thing is to buy and add only pre-mixed 50/50, which has de-mineralized water to help the additives work. Be careful not to allow the antifreeze concentration to get too high by repeatedly adding straight antifreeze. “Too much antifreeze is like a gel,” Sholly says.

What happens if you don’t maintain the coolant? You can have serious damage to the engine itself. But even considering just the radiator, you can have all kinds of trouble, partly because untreated coolant gets like an acid. Acid works with the corrosion caused by bad coolant to create damage and leaks.

Many radiators today use plastic top and bottom tanks sealed with thick gaskets. The tank is crimped around the gasket and the header plate at the top or bottom of the core to hold the gasket in place and make a seal.

When the coolant goes bad, it often erodes the gasket, Mascuch and Sholly say. Soon, much of the thickness is gone, the gasket no longer seals, and you get a big leak. Another problem is with the tank itself. The acid can erode the tank on the inside as the coolant flows through it, washing the plastic away, it until it becomes quite thin.

“Corrosion blocks the tubes and slows the flow,” Mascuch says. “Pressure then builds up in the system; even the normal operating pressure under favorable road conditions will be higher. This puts excess pressure on the tank tabs, and they break. Or the combination of pressure and temperature and erosion of the plastic causes the tank to crack.”

These effects may also cause the tank to warp and not fit.

The clogged tubes may also corrode through and leak, necessitating a repair or core replacement. The acid actually corrodes the lead in the original solder, just as it corrodes those lead battery terminals, and that can make the tubes leak at the ends even if they don’t rust through.

The cooling fan and thermostat
During highway operation on level roads, the airflow needed to keep the radiator working is provided by ram air. But when running in traffic or climbing steep grades at lower speeds, the cooling fan clutch engages to provide airflow. This system is subject to mechanical problems with the clutch, or on early models with a separate sensor and wiring for the fan, wiring and sensor failures. These can result in higher-than-normal operating temperatures under certain conditions. That means extra radiator stress.

You’ll hear the fan come on and often feel it because of the drag. Keep your eye on the temperature gauge and remember the point when the fan engages, usually 15 degrees F. or so beyond the point where the thermostat opens. If the fan starts coming on at too high a temperature or fails to come on at all, have the problem repaired right away.

The thermostat is another critical part, and it can become lazy and open late. This, too, will increase the pressure in the system and put unnecessary stress on the radiator.

Although it is normal for the operating temperature to rise somewhat in warmer weather or when running under heavier loads, it should still remain within a narrow range. If it creeps upward, have the thermostat checked.

The thermostat should ideally be replaced every year or two, anyway, Sholly says. Maximum life is five to seven years. She says the thermostatic spring goes bad eventually and, “Don’t wait until it sticks and gives you more problems.”

Sholly also recommends using only an OEM unit, as some aftermarket units may be unreliable and not keep the engine at the proper temperature. Her shop has solved more than a few troubles by replacing aftermarket thermostats with original equipment. And always use new gaskets and seals with the ‘stat.

Getting the repair
Once you develop a radiator leak, there’s only one thing to do – get it repaired.

“Once you have a problem, don’t wait to get it fixed,” Sholly says. “The longer you wait, the more it will cost. The damaged area often grows, so nip it in the bud.”

Don’t put sealers into the system to stop a leak. They can clog the whole system and often increase the cost of getting a radiator repaired because of time needed to clean out the tubes or other passages.

She says it’s better to take your vehicle directly to a shop that specializes in radiators. “Not anyone can repair a radiator properly,” she says. And why pay a markup charged by a general repair shop or dealer? You can look up the location of the nearest shop on the NARSA (National Auto Radiator Service Association) website (see “For More Information”).

The radiator shop should be clean because that reflects on the quality of the job. Is it well organized and equipped? Mike and Daughter’s has a fork lift to lift parts, a substantial lift for vehicles, a number of large cleaning tanks and a good deal of other specialized equipment. (Proper chemical cleaning can clear blocked tubes and save a core.)

Do the shop managers know the answers to your questions and answer them without hesitating? Do they seem confident in knowing what your problem is and how to fix it? Are their technicians experienced? One Mike and Daughter’s employees has been doing this for 30 years. Sholly concludes, “Radiators should be what they specialize in, and not a sideline.”

They should also be straight with customers and show them problem areas and damaged parts they have replaced. Also, it’s necessary to look at the entire system, not just the radiator. For example, the cause of an overheating problem might be a water pump with corroded impeller blades, another symptom of which would be poor heat in the cab. If the shop doesn’t look at your problem in this way, you should go somewhere else.

If you’ve had chronic leakage not due to neglect, you may want to get your radiator completely re-cored, Sholly says. That means new tubes and fins, with the original tanks re-mounted onto the new core, if they are in good condition. A high-quality new core purchased in the aftermarket can actually be better than original equipment, with thicker tubes and fins, and more solder. This will solve chronic leakage problems in many cases.

“Some people just want it cheap,” Sholly says. “We like to put it back in original condition, or better, to give you equal or increased cooling efficiency. As a result, we have very few customer complaints. The key benefit of spending more on the repair is reduced downtime.”

For further information, please contact the following:
Mike and Daughter
Radiator Aid
Lancaster, Pa.
(717) 394-0184

National Auto Radiator
Service Association
(856) 439-9596

Proliance International, Inc.
(800) 755-2160