ROYAL FLUSH OR ROYAL PAIN? BY PAUL WEISSLER Once-basic maintenance services, like draining then filling the cooling system with fresh coolant, are no longer basic. Today, specialized tools and techniques must be employed to prevent unnecessary pain and suffering. There are a couple of service jobs you probably see fairly often involving the vehicle cooling system. We ll loosely categorize them as the beauty and the beast. One is finding and fixing intake manifold gasket coolant leaks on General Motors V6 pushrod engines; the other is draining and filling the system on a host of cars, trucks and SUVs. Let s take an in-depth look at the drain & fill operation the beast first. In theory, draining and filling the cooling system should be pretty straightforward, but on most vehicles it s become a beast of a job. And the situation will be getting worse, as we see more and more vehicles with ever more complex coolant flow paths. Furthermore, the long coolant service intervals recommended by all manufacturers today means that the coolant usually is in great need of replacement when the motorist finally does decide to get the job done. Often, this decision is made because a hose or gasket joint has been leaking, and the system has been topped up periodically with who-knows-what in terms of antifreeze and, almost surely, tap water of unknown quality. Our recommendation for a first drain & refill step is to check both the coolant level and the concentration. Next, pressure-test the system and inspect for leaks, followed by repair if any leaks are found. If there s evidence of leakage but you can t find it, pour trace dye into the system and ask the motorist to drive for a few days to circulate it. In a relatively late-model vehicle, if the coolant is close to the marked level in the reservoir, is topped up in the radiator (if there s a way to check that), looks clean and the refractometer says the mixture is within a whisker of 50-50, those Photoillustration: Harold A. Perry; images: Thinkstock 18 August 2011
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There s a wide assortment of drain & fill machines on the market, and here are several examples (clockwise, from top left): Yellow Jacket, FloDynamics, RTI and MotorVac. Look for the operating features that are important to you, such as the ability to easily switch antifreeze types, backflush capability, easy-to-use adapters. Photos: Paul Weissler are good signs. The coolant may be ready for a change, but at least it probably hasn t been badly contaminated since it was installed at the factory. However, be sure to ask. The motorist may admit to some do-it-yourself service that can change your opinion. In fact, if you see an antifreeze dye color that doesn t match what you expect in the OE coolant, be very sure to ask. Dye color doesn t mean anything from the standpoint of antifreeze performance, but it might indicate that there s some cross-contamination. Or it might not. The aftermarket replacement for DexCool could be yellow (Prestone), not orange/pink. The aftermarket replacement for Chrysler s orange is yellow (Zerex G-05 or Havoline Custom Made). One aftermarket replacement for all Asian formulas (which could be pink, blue or green) is Zerex Asian Vehicle Long Life, which is pink. Everything could be fine, but the more information you have, the better job you can do. We know some shops that flush every system 20 August 2011
Using a coolant air bleed kit or a venturi wand from a drain & fill machine, as shown here, is the simplest way to remove used coolant from reservoirs. and replace with conventional American green a two-year formula, not the OE extended-life antifreezes (and not the best choice). The ugly truth is that it s impossible to fully drain a cooling system on almost any modern car or truck with a procedure short of pulling the engine, turning it upside down and tilting it. And with all the nooks and crevices, we re not even sure that would work on all engines. The second surest way to drain a modern cooling system is to use a premium drain & fill machine, which will probably replace 85% to 90% of the coolant. Third best: Drain the radiator and block (which may involve disconnecting the lower radiator hose), draw all the coolant out of the reservoir and run water through the heater until it runs clear. Then fill the system as full as possible, including the reservoir, warm up the engine and let it cool down, then fill with plain water and top up. Special funnels that fit in the radiator neck are helpful if there actually is a radiator fill neck. But with fewer vehicles these days having one, such funnels have limited value. The by-the-book percentage procedure is to repeat the cooldown/warm-up and then drain & fill twice more. That should get about 90% of the old coolant out of the system. Then get enough water out of the system perhaps there s enough in the radiator and reservoir to add enough antifreeze for a 50-50 mix. If the cooling system has an inlet thermostat, make it standard procedure to pour in fresh coolant through the upper radiator hose. However, if the stat is in the cylinder head at the outlet to the radiator, you ll have to remove the thermostat first no way around that short of just not doing it. But then the results are your responsibility. Bottom line: This ain t gonna happen, not in any repair shop I ve visited lately. Maybe a dedicated do-it-yourselfer with a spare weekend will do a triple-drain/thermocycle/refill. But let s get real here. The fact is that a triple drain, thermocycle and refill would likely tie up a service bay for a full day (even if the technician isn t actually working on the system more than an hour total). Actually, the technician will drain the radiator, maybe disconnect the lower hose (or, if there s a block drain, open that) and suck the coolant out of the reservoir with a drain & fill machine wand or venturi vacuum cooling system kit, if he has one. And then he ll do his best to fill the system. If he doesn t get it adequately drained, the left-in debris eventually will restrict the heater and/or radiator. If he doesn t get it completely filled, the system will have air pockets, so it may not cool properly in summer or provide adequate heat in winter. Look for air bleeds beyond those in plain view and open them prior to a drain & fill operation, particularly if you re doing the job by hand, without a machine. Heater To alleviate trapped air bubbles, fill the rear heater separately on a vehicle that has front and rear heaters. So how do you make sure the system has a fresh fill when you release the vehicle to the customer? A drain & fill machine, with the flushing feature, still is the best choice. There are several choices from large, reputable manufacturers, and we ll let you sort through the operating features of each to make a decision. The lineup of major suppliers includes FloDynamics, Motorvac, Yellow Jacket (Ritchie), Robinair, Bosch/RTI Technologies, Snap-on, Viper (Clore Equipment) and Wynn s. The manufacturers typically offer a full line of choices. Some basic machines may be designed to simply draw the coolant out of the radiator, but the manufacturer also will offer full-feature drain & fill equipment, with backflush adapters (although they may be optional). And they would be our choice. What also makes the right machine a superior choice is that you can use a 50-50 mix that includes distilled or deionized water. Unless you know the tap water in your area is nearly mineral free, there s nothing that can beat the treated water, which is what they use in the 50-50 mix. Of course, you pay almost as much for 50-50 as you do for pure antifreeze, so it s really not an economical purchase. A jug of pure water is under $1 at supermarkets and discount stores. And it s really one of the secrets behind 22 August 2011
Dual cooling systems are common on hybrids and on the new electric-drive cars. This Chevy Volt has three cooling systems (reservoirs indicated by the arrows) one 20-psi system for the engine with the reservoir at the left rear, and two 5-psi systems with reservoirs front and center (one for the motor electronics, one for the battery pack). All three use the same DexCool antifreeze/coolant formulas. the long coolant intervals that the carmakers specify for new systems: no debris, a perfect fill and brand-new gaskets and hose connections there s nothing better. By the time the vehicle gets to your shop, the factory-fill 50-50 mix could be anything, which is why we suggested earlier that you check the concentration before you even start servicing the system. The second choice is to drain as completely as possible typically the radiator, engine (from the lower hose or a drain plug) and the reservoir but maybe not as much as you might get out. For example, blowing shop air through a heater core would force out some coolant but leave an air pocket you might have trouble clearing. We call this procedure ineffective or worse, and put it at the top of the do-not-do list. But like many procedures, there s an exception: If the coolant is old and there seems to be a restricted heater, leaving the coolant in the heater doesn t do the system any good. Backflushing with water does help and at least the core will remain filled. In fact, if the coolant is dirty, a drain & fill machine with a flush feature is about the only way to clean out the system. You can try chemical cleaners, but then you have to get them out, and here again, a machine is the only single-procedure approach that has a chance. One flushing device, the Hecat coolant pulsator, uses a hammerlike delivery of water and shop air. Cooling system specialists find it often clears enough plugging to restore reasonable performance, if not the performance level of a new core. So a vacuum refill of the heater core follows this procedure and would be worth the effort. Of course, we recognize that heater performance is a winter service issue, so unless the motorist also says that the heater didn t work in winter and wants you to do something now, you can t justify going overboard in midsummer. You could ask, or even check heater operation, but that s about it. Without the drain/flush/fill machine, when it s time to fill, you have to do everything right. If the vehicle is an SUV or minivan with a rear heater, and there has been a leak that you repaired, there s an obvious problem when you jack up the front of the vehicle to help bleed air from the front end: The rear heater will be below the front of the vehicle and never bleed air. The only answer is to fill the rear heater separately, and that s true After removing the manifold gasket, clean the surface. You can use a die grinder and metal-safe cleaning disc, as shown here. Premium replacement gaskets from reliable aftermarket sources provide long-life sealing of the cooling system. 26 August 2011
even when you re servicing the system with a machine. For the front system, one standard operating procedure, of course, is (with the front jacked up) to open all the air bleed valves and start filling. Although some air bleeds are in plain view and readily accessible, others take some looking for, including checking the vehicle service information. Open the bleeds. Next, run the engine at idle so air bubbles will rise to the surface of the coolant, and top up slowly. If the radiator has a fill neck, use a funnel, which allows coolant to flow into the system as air bubbles rise out from the neck. When you see solid streams of coolant from the bleed valves, close them and finish topping up. Ask the customer to return in a week for a free check and top-up. An alternative is the use of a vacuum fill kit, such as the UView Air Lift and Bright Solutions Radiator Miser, in which you pull a vacuum to prevent air bubbles. These kits attach to the radiator fill neck and work best if they aren t expected to pull a deep vacuum through the entire cooling system. So you ll do best to manually fill the block first, and start with an empty radiator. Most hybrid vehicles have two cooling systems one for the motor electronics 8 4 2 6 To prevent leaks when replacing an intake manifold gasket, torque all bolts to factory specs, using a torque wrench you know is accurately calibrated. and one for the engine. What may set a new standard for a beast of a system to fill is the Chevy Volt, because it has a separate cooling system for the high-voltage battery pack. First, there s a heat exchanger with both coolant and a/c refrigerant in case battery temperature gets too high. Second, if you have to repair an antifreeze/coolant leak from the battery case system, there s a double challenge. For the refill you have to use a vacuum lift kit, but even that may not get all the air out of a Chevy Volt. And with 7 3 1 5 Always follow the vehicle manufacturer s torque sequence. For example, for the lower intake manifold gasket on 60 GM V6s illustrated here, the torque is specified in two stages, with separate specs for each set of four bolts. First tighten all bolts to 62 in.-lbs., then bolts 1-2-3-4 to 9.5 ft.-lbs. and bolts 5-6-7-8 to 18 ft.-lbs. those expensive lithium-ion batteries, removing all the air from the antifreeze cooling system is a must. The final procedure specified by General Motors is to drive the car for five miles in a slalom manner. We suggest you do this in an empty parking lot. The Nissan Leaf, on the other hand, which has no engine and uses air cooling for the batteries, has two antifreeze/water cooling systems one (with the radiator) for the motor electronics and the high-voltage battery charger (yes, the charger, not the batteries), and one for the heater, which is a PTC element. Among the less obvious results of neglected engine coolant is a plugged heat - er core or a water pump eroded and corroded into a weak state. Installing a new heater core is not an easy job. And there sure are some V6 water pumps that also go into the beast category, such as those recessed pumps on transverse front-drive cars. So they can be a tough full-day (or longer) job that can be a difficult sell unless the system is leaking visibly and requiring regular top-ups. Fortunately, they don t occur with the frequency of those top-of-the-list intake manifold gasket leaks we mentioned at the start of this report. If you do a good job on coolant service, they won t make the list at all. We remember when they first began to surface as a service issue, and there was a new gasket kit to address the problem seemingly every week or so, both from the OEMs and the aftermarket. 28 August 2011
The problem turned out to be a major headache for the OEMs and their dealers, as the cars were under warranty. The elimination of nylon from gasket carriers and silicone from gaskets dealt with a materials compatibility problem with one of the antifreeze additives in DexCool. Torque limiter buttons at bolt holes and metal for the gasket carriers were among the changes made to improve sealing. However, they still are tough sealing jobs, and even if they last longer, the gaskets are a replacement job that seems to show up frequently. A careful execution is almost a full-day job, so it s a big labor ticket. When you do it right, it turns out well and lasts. In the category of jobs you see on the schedule, today replacing leaking intake manifold gaskets has to be considered a beauty of a job. By now, most independent shops have a routine for them, including the purchase of a premium aftermarket gasket kit. Although disassembly takes time, careful cleaning of the gasket surfaces should be a priority. When a new gasket is in position with the manifold section over it, be sure to use a torque wrench and follow the recommended tightening sequence. These gaskets don t take high torque. But they have to be properly seated, and although the torque buttons help, the torque wrench has to be first, accurate, and second, used per the sequence spec. We ve cringed as we watch technicians finish using the popular click-off torque wrench and then just toss it into the toolbox. That s a pair of no-nos. Instead, when you re done, back off the micrometer adjuster to zero, so the spring inside doesn t take a set. Second, place it in your tool chest, do not toss it it isn t some box or open-end wrench. We ll add a third step: Periodically check the accuracy of the torque wrench. This is a service that the tool companies offer, but rarely get customers for, we hear. An alternative is to keep one of those inexpensive torque beam wrenches safely stored as a comparison unit. They re almost worthless for underhood work, because they rarely will fit into anything but a wide-open area (not many of those today). So just take it out once in a while, torque a wideopen bolt to a few common torque specs, and recheck with the click-off wrench set to each of those numbers. If you ve handled the click-off wrench reasonably, it should remain within 10% to 15% of what you get with the beam wrench. If you see a big difference, you know it s time to get it recalibrated. The manifold bolts on GM s 60 V6 should always be replaced. As noted, this is a big-ticket job, very straightforward work, and you don t want to do it again in a year or so. Yes, the warranty you give will have run out, but do you really think you can point to a piece of paper on this kind of job? If it s a 3800 V8 (the 90 engine), the bolts are reusable. This article can be found online at www.motormagazine.com. Circle #14 August 2011 29