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new in the last year alone is enough to call for a RAM implant in your cranial hard drive. While the car companies keep talking about the unrepairable radiator, NARSA shops keep learning new ways to repair them. Having the OE radiator repaired is more than just a way to save your customers money. Some of these radiators are engineered to provide high airflow, and it’s tough to get adequate cooling in severe conditions without
Photos: Paul Weissler
he National Automotive Radiator Service Association (NARSA) annual convention held last March in Reno, Nevada, with close to 2000 people from radiator shops and the supplier industry in attendance must have been just one big party. After all, what’s changed in cooling systems recently besides a long-life orange antifreeze? Well, a lot has changed, and what’s
If the plastic tank on a Chrysler four-cylinder minivan radiator is cracked, you can repair it with a new plastic tank (bottom, in photo). If there’s a stress crack on the header but the core is in good shape, the crack can be repaired and a retrofit brass tank (top) soldered on.
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them. They’re expensive, and the premium aftermarket models aren’t a lot cheaper. Here are a couple of cases in point, from the Big 3: Chrysler’s plastic tank copper/brass radiators have long suffered from stress cracks along the header. When that happens, the only durable fix has been a new core, because any repair of the crack itself wouldn’t hold up under the thermal and structural stresses. Now there’s an alternative for 1984-89 minivans with the fourcylinder engine—a brass tank can be soldered to a repaired core, which eliminates the stress. The retrofit brass tank was shown at the convention by Air Radiator Supply, of Carson, California (800-352-4277). So if the core is stress-cracked but in otherwise good condition, now there’s an inexpensive fix available. When Ford converted to atmospheric brazing of its radiators—a changeover from the previously used vacuum brazing process—it looked as if a popular repair was out the window. You see, vacuum brazing requires an epoxy seal that eventually lifts out, but radiator shops have the equipment to remove the old epoxy and install a new film. That epoxy seal is gone with the new atmospheric
The resourceful aftermarket continues to mend ‘unfixable’ OE radiators. Here are some of the most interesting applications exchanged at the annual NARSA convention. BY PAUL WEISSLER design, and the crimp tabs will no longer withstand an unbend-and-recrimp, says Ford. That seems to bury such popular remedies as a new gasket or a new tank. However, shops that do a lot of epoxy repairs have found that when the gasket leaks or the tank cracks, they can still repair the radiator. They unbend the crimps, fill the gasket trough with epoxy, then generously fill the joint between the tabs and the
tank with more epoxy, recrimp the tabs and let the whole thing cure. “Won’t last a year,” scoffed a Ford engineer. “We’ve been doing it for three years without a comeback,” replied a rad shop owner. As more of these radiators come into the service market, the companies that make aftermarket crimp strips for broken header tabs have said they’ll be adding these items to cover Ford. If you have to replace a copper/brass
radiator on a GM vehicle, the GM-Delphi/Harrison replacement will have an aluminum core. Copper/brass production at GM is over. The aluminum design will “almost” bolt in to replace the copper/brass. A couple of “howevers,” though: 1. The integral transmission oil cooler may be longer than the one on the copper/brass, so you’ll have to bend the cooler lines to make the new connections. 2. If the old radiator had a low-coolant sensor in the tank, you may
These cutaway and overhead views of a Ford atmosphere-brazed radiator shows how filling the gasket trough and then the header-to-tank joint with epoxy can produce a durable repair of a leaking gasket with the tabs that Ford recommends against recrimping. Score one for the rad shops who have been doing this for a few years.
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HOT RADIATOR REPAIRS have to drill out the probe hole that’s provided on the new aluminum job with a 3⁄16-inch bit. Just put a stop on it, so it doesn’t go in more than 3⁄4 inch and hit the oil cooler.
Are Aluminum Radiators Really Bulletproof? Aluminum radiators have the potential for long life and good performance, and they’re light in weight. And even though every car manufacturer has switched to aluminum, they’re not bulletproof. NARSA conventions get a regular dose of warnings from the car manufacturers on what causes them to fail. The killers: •Low antifreeze concentration. In warm-weather areas, it’s common to see antifreeze concentrations of about 20% from repeated top-ups with water. These low concentrations have been shown in laboratory tests to be worse, actually, than no antifreeze at all, from a standpoint of corrosion protection. That’s because the resulting low inhibitor levels leave small areas of radiator tubing open to concentrated attack from corrosive water. The result is pitting perforation of the radiator tubes, and leaks that require a new core to fix. •Electrolysis. The coolant is part of the engine, so some current flow is almost inevitable, because the vehicle’s grounding system is not perfect. Probe the coolant, and if you get a reading of .3 volt or higher, the radiator is a candidate for a failure from corrosion buildup in the tubes, particularly because the plastic tanks used today do not provide a ground path. A .3-volt reading used to be tolerable on the old copper/brass radiators in systems with cast-iron engines, but not with aluminum. In fact, an illustration was displayed at the NARSA convention of a radiator that was plugged with corrosion in just a month and a few thousand miles because a shop had grounded an add-on horn system to a radiator bracket. When you find high voltage, isolate the problem by activating and unplugging circuits, particularly the electric cooling fan. A poor motor ground is a common cause.
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This radiator became almost completely plugged from electrolysis after just a month and a few thousand miles of operation because an add-on horn system was grounded to a radiator mounting bracket.
It’s important to be up-to-date on plastic tank gaskets. The gasket on the left is a narrower design, released by GM as a factory fix for the original design, shown at right and produced by an aftermarket manufacturer. The original design has a wide inner lip, and that lip covers part of the tops of the radiator tubes, restricting coolant flow.
•Plastic tank gasket leakage. Except for rare cases, you can’t just recrimp header tabs. You’ve got to replace the old gasket using the right kind of plastic tank clamps—and enough of them, properly spaced. You’ve also got to use the right gasket, and that may call for making a choice between an OE and an aftermarket design. In some cases, the aftermarket gasket is redesigned to correct an OE problem that surfaced after the warranty period. In other cases, the factory may pick up a problem from its early dealer feedback and redesign a gasket, while the aftermarket replacement still reflects the original design. You can get the latest information from suppliers who carry both, such as Plastank, in San Luis Abispo, California (800-562-5896).
The Copper/Brass Comeback
GM’s phaseout makes it obvious that aluminum cores have taken over the automotive radiator market, and are making inroads into the heavy-duty arena. After all, the EPA considers lead solder a hazardous waste, and aluminum saves weight. But the copper industry hasn’t just been sitting around watching. It helped develop improved assembly processes, including CuproBraze, a totally new procedure that eliminates soldering and produces a brazed copper/brass radiator on a modified aluminum radiator assembly line. There’s no solder in the process, and the quality of the finished product ends up as good as aluminum, says the copper industry. More im-
er reference on plastic tank gasket leakage). Unless you’re sure of what you’re doing, you may have to spring for the sealed case. GM has been supplying balanced blower fan and motor assemblies for some applications for years. But if you run into a low-airflow situation on a car that’s got a replacement motor, the problem could be that someone who got the old blower wheel off and managed to attach it to a new motor didn’t get it as tight on the shaft as he thought. If the wheel is slipping, the airflow drops. Low current draw is a tipoff to an airflow problem, ACDelco’s John Bruner noted at the NARSA convention. However, he also pointed out, the real culprit could be a plugged cabin air filter or even leaves stuck in the outside air inlet duct, either of which is a simple fix. By the way, those cabin air filters have a rated life of only about a year or 20,000 miles. Sometimes less. Check the owner’s manual. Rad shop owners agree that aftermarket suppliers of blower motors need to do something to provide serviceable alternatives for the one-piece OE blowers, such as GM’s newest design on the ’98 Cadillac Seville.
Copper/brass isn’t completely dead. This new Chrysler minivan radiator (above) is the first to be produced with the CuproBraze process, which mimics the method used for aluminum radiators, but which is more forgiving in the production process. So it should find favor with aftermarket manufacturers.
The new Caddy Seville blower motor and fan (notice it’s not a squirrel cage) is a one-piece assembly for low noise and vibration. At this point, there’s no way to replace just the motor.
portant, because production costs are lower, the process is friendlier to the smaller aftermarket manufacturer. A radiator can be repaired as easily as any old copper/brass—using lead-free solder, if necessary. The first CuproBraze radiators, for Chrysler minivans, are rolling off an assembly line at Universal Auto Radiator, in Pittsburgh (412-481-9490). The new radiators were developed in a research project by the Copper Development Association, and optimized for low weight and heat transfer that’s competitive with aluminum.
When You Can’t Repair, Replace Remember when the car companies used to complain about parts replacers in the repair shop? Now the inde-
Hot in Summer, Cold in Winter pendent specialist faces new cooling system/HVAC repair challenges beyond what radiator shops have learned to do with radiators. NARSA members at the convention saw the latest in Ford and GM moves to improve product quality and “ensure quality repair” by supplying only complete components. At Ford, there’s a trend toward dropping the detail parts inside the sonically welded sections of its HVAC cases, so you have to replace the whole assembly. HVAC specialists still plan to use their hot knives to cut open the case and install replacement aftermarket parts. However, there may be a problem in getting some of the redesigned OE parts, such as specially engineered seals to solve leakage and drainage problems (refer to our earli-
It would seem that if an engine runs hot in the summer, it should produce good heat in the winter. Not so, and although there are lots of “one-ofs” that make for good barroom talk, NARSA members told MOTOR about some engines that come up in high numbers. Here’s one that makes for strange troubleshooting, because the engine runs hot while the radiator temperatures, as measured with an infrared thermometer, are normal to low. In a GM full-size G-van with the 5.0-liter V8, where the cap is on the radiator inlet tank, a shop owner noticed that when he blipped the throttle with the engine at hot idle, the upper radiator hose (obviously heat/age-weakened) collapsed slightly. He took off the cap, blipped the throttle again and the coolant level in the fill neck dropped,
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HOT RADIATOR REPAIRS then shot back up, sort of like a a heater core on most late-modgeyser. The coolant temperature el vehicles is close to a day, and was fluctuating between 130°F, the overall cost leads many moEngine when the coolant level dropped, torists to try and seal the leaks Appearance Cover and 150°, when it played Old with as much Stop-Leak as it Faithful. At the heater inlet, the takes. But the heater core pascoolant temperature read sages (and many other passages 175°F. You can add, perhaps, in the system) are much nar10° to all these readings berower than the radiator’s, so cause of infrared gun variation, they may plug even if the radiabut still.... tor remains in acceptable condiSounds like a restricted radition. Unless the flow of coolant Cooling System ator, at least. But they disconto the radiator is at spec, even a Fill Plug nected the hoses and checked clean radiator can’t stop an enthe flow through the radiator itgine from overheating. self, and it was acceptable. Second, ever since GM startHowever, there was virtually no ed using Stop-Leak on the asflow through the heater core. sembly line many years ago, it’s Further diagnosis—including a viewed almost as a good “predetailed questioning of the ventive maintenance” item. truck’s new owner—revealed Some people empty a can into that the heater core was leaking the system every year. Ouch! and he put in a can of sealer. Better Ideas for Apparently, the previous owner Purging Air had done the same thing to try to stop the persistent leak. Ford’s 4.6-liter four-valve V8 still has the engine Air locks in the cooling system When the shop’s crew back- coolant fill plug in the crossover pipe at the top are becoming increasingly more flushed the entire system, it be- front of the engine. If the engine has a beauty cov- difficult to correct. Ford has gan to cough up chunks of seal- er, as on the Continental and Mark VIII, you have to been living with a couple of remove it for access. problem systems—the 4.6-liter er all over the place. Result: V8 in the big sedans, Mustang and The low flow through the radiator ble-cooled the coolant,” producing Mark VIII, and the 3.0-liter V6 in the (apparently from some plugging at those low coolant temperatures. Nissan-designed (but Ford-built) the water pump inlet and through the NARSA members told us of many Mercury Villager/Nissan Quest. Ford cooling passages of the engine) exsimilar problems, apparently with two discussed the issues in detail at the plained the geyser effect that “douroot causes. First, the labor to replace Illustrations: Harold Perry
Ford 4.6L 4-Valve V8
Mercury Villager/Nissan Quest 3.0L V6 Radiator Air Bleed Plug
Back of Engine
Engine Air Bleed Plug
Allen Wrench
Loosen the radiator air bleed plug with three turns of an Allen wrench and remove the engine air bleed plug (as shown) before you start filling the cooling system on these minivans. Then fill the radiator. Close the rad plug when it starts dripping. Reinstall the engine plug when coolant flows from the hole.
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HOT RADIATOR REPAIRS NARSA meeting, and offered its “better ideas.” The 4.6 two-valve engine coolant fill problem was “fixed” by moving the pressurized reservoir to the fan shroud, where it’s at the high point of the system. The 4.6 four-valve engine still has a coolant crossover pipe at the top front of the engine, and you have to remove the plug in that pipe and fill the engine through the opening. If you simply pour coolant into the reservoir, it won’t fill the engine. And despite the fact that the reservoir is pressurized, it may take forever to burp. The engine will overheat (and the heater won’t work well in winter). Nissan has a favorite way of burping
its cooling systems, with some variations from model to model. It’s effective if you have the patience to use the method, and not stop until a system has “bubbled” out. Ford found that few dealer techs were patient enough to use the Nissan method (check your MOTOR/ALLDATA system for the gory details) and developed the following American-style alternative. It doesn’t provide instant gratification either, but it’s a lot less tedious: In the case of the Villager/Quest, jack up the front of the minivan as high as you can, stopping only when the tailpipe is grazing the shop floor. Loosen the air bleed plug on the radiator three turns, remove the engine
air bleed plug and fill the radiator until coolant drips from its plug hole. Then retighten the radiator plug. Continue to add coolant until it comes out of the engine air bleed hole. Then reinstall and tighten the engine air bleed plug. Top up the radiator and fill the reservoir to the Max line. Reinstall the radiator cap, but turn it just to the first catch. Then, with front and rear heater systems on Max Heat and High blower, run the engine at about 2000 rpm to let it burp. This could take 20 minutes, so keep checking the coolant level and add to the reservoir to keep the level at Max. When the level is steady, check the
Towing Capacity vs. Cooling Capacity
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owing capacity is important for two reasons: First, if you’re buying a new truck or SUV for the shop, you may have to pull a load, even if towing in customers’ cars is not the purpose. Second, if a customer’s truck or SUV overheats, there’s a chance the towing capacity is being exceeded. You’d think it would be simple to determine towing capacity, but as we found out in preparing the ‘98 truck report last February, it isn’t. The information on new vehicles may change many times, and even carryover vehicles may get a change in these ratings from year to year. The case of three Chrysler vehicles—the Jeep Grand Cherokee, Dodge Dakota and Dodge Durango, a new SUV based on the Dakota—is a good example. From the time of the initial Durango announcement until the final version (with the 5.9-liter V8) rolled out this spring, the towing capacity figures on the Durango were changing even faster than Chrysler’s own people could keep track of. When consumers look at a truck, they tend to look at peak towing capacity. They believe that the biggest engine can tow the most trailer weight. Not true. The Jeep Grand Cherokee 5.9 Limited (with the big 360 V8) is being promoted as a 0-to-60 performance truck. Its towing capacity is just 5000 pounds, with a 3.73:1 the only rear axle ratio available. The limitation is imposed by the cooling system, which has an electric fan to reduce the power draw for acceleration. The smaller 5.2 V8 has a clutch fan, and its towing capacity is 6500 pounds. But there’s a retrofit clutch fan kit available for the 5.9 V8 if the 6500-pound towing capacity is necessary. The Dakota and Durango are both haulers. In fact, the Durango is being promoted as a high-tow-capacity SUV. So both get clutch fans for maximum cooling. In some trucks, including these, the towing capacity with 4WD is lower because of the limits of the transfer case or the
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transmission (in this case, some manuals have more, others less than the automatic) and the extra vehicle weight. And if we’re talking truck cabs, a club or crew cab that holds extra passengers is obviously heavier than a regular cab, and that can make a difference of a few hundred pounds in towing capacity. Another key factor that affects towing is rear axle ratio. As you’ll see, it makes one of the biggest differences in the Durango. Here are some automatic transmission examples:
Engine
3.55 Axle
3.92 Axle
5.2 V8 5.9 V8
4300 lbs. 5600 lbs.
5600 lbs. 7200 lbs.
Although the Durango is based on the Dakota chassis, the Dakota has much higher towing capacities throughout the range of axle ratios. Here are some examples with the 5.2 V8 and automatic transmission:
3.55 axle: 3.92 axle:
Dakota Regular Cab
Durango
5100 lbs. 6700 lbs.
4300 lbs. 5600 lbs.
Bottom line is that lots of buyers of trucks and SUVs (often for the first time) may think they’ve bought the peak towing capacity, when they haven’t. So their introduction to the truth may be when the vehicle overheats and comes into your shop on a hook. You’ve got to consider everything, particularly if you’re trying to diagnose an overheat. This includes trying to determine if the truck is pulling too much weight. If the owner of a Dakota club cab thinks he can pull 6700 pounds with three large friends in the cab but the wrong driveline configuration, an overheat should not be a surprise.—P.W.
temperature at the front and rear heater/floor registers. If they’re the same (higher than 135°F at least), you’re done. If the rear system temperature is noticeably lower than the front, there’s an air lock in the rear and you’ll have to keep burping. Of course, you could just use a drain & fill machine. It’s not high-volume work for most independent garages, so the machine is viewed as a questionable investment. However, we’re seeing more and more airlock problem vehicles, so maybe you’ve got to bite the bullet. Car dealers and radiator shops are starting to get the message. Some NARSA members at the convention reported that one of the oldest causes of air ingestion seems to have been forgotten—a defective airsealing gasket on the pressure cap. If that gasket is deteriorated, it allows air to be drawn into the system during cooldown. A reservoir that remains overfull after cooldown is a tip-off.
‘Quiet’ Engineering Means Tough Clutch Fan Diagnosis
There are still lots of clutch fans around these days, on luxury rear-drive cars and almost all trucks. You can’t always rely on a blob of silicone at the clutch bearing or a loose fan blade as sure indicators of a slipping fan clutch anymore. And thanks to the intense design work to produce quieter fans for customer satisfaction, you can’t rely on the high roar of an engaged clutch anymore, either. It also isn’t easy to aim an infrared thermometer into today’s tight-clearance shrouds to see what the air temperature is. So what kind of diagnosis can pinpoint a problem? NARSA shops are doing several things. One is taping a pyrometer snake probe in a clear space inside the shroud, and checking to see if air temperature peaks in the range of 150° to 190°F. Another is checking the fan with a photocell tachometer,
an inexpensive tool you may already have for checking idle speed on diesels. Just put a piece of tape on a fan blade tip, aim the tach and when the engine is warmed up, you should see the fan speed rise uniformly with engine rpm. Today’s fans typically peak at about 2000 rpm, but a bad clutch won’t allow it to get anywhere close to that. The NARSA convention also looked at air deflectors, radiator perimeter seals, electric fan control systems, new thermostats, charge-air cooler diagnosis and repair and a lot of other stuff. But hey, you had to be there to get it all. For a free copy of this article, write to: Fulfillment Dept., MOTOR Magazine, 5600 Crooks Rd., Troy, MI 48098. Additional copies are $2 each. Send check or money order.
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