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Cloyes: How To Service Timing Chain Components 2007-2015 GM High Feature V6


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    • By Counterman
      It’s no secret that the heart of an electric vehicle is its high-voltage (HV) battery.
      There are a number of electrical circuits and protection devices found within an HV battery assembly. These circuits work in conjunction with the vehicle’s battery-management system (BMS) to ensure safety and battery longevity.
      It’s not uncommon to have several hundred lithium cells in an EV and more than 25 cells in a hybrid vehicle. These cells must be properly balanced to one another, while their temperature and the packs’ overall voltage and amperage must be closely monitored by the BMS.
      Often, when a battery has been properly tested and is found to be bad, a remanufactured battery may be the best option due to the price.
      Typically, remanufactured batteries include a number of improvements, such as nickel-plated terminals (to avoid corrosion); optimized cell mounting to eliminate the risk of case cracking due to vibrations; individual cell testing and balancing of the pack; and other comprehensive testing to ensure long life.
      For example, Dorman’s remanufactured hybrid battery pack for the 2004-2009 Toyota Prius features “nickel-plated bus bars and corrosion-resistant terminals for increased reliability,” according to the Dorman website, while “proprietary software uses [a] multi-dimensional grading process to select battery cells that will perform ideally together.” The battery packs are subjected to “multiple stringent validation gateways, including on-vehicle tests using EPA performance standards,” according to the company.
      Remanufactured batteries should be an attractive option for your customers – especially those who own hybrid vehicles, as they’re likely seeking a cost-effective solution. Dorman’s remanufactured hybrid battery packs come with a two-year warranty, according to a recent sales flyer, compared to the eight- to 10-year warranty for most OE batteries. Generally speaking, however, remanufactured batteries should have the same life expectancy as a new one.
      It’s important to note that when a remanufactured battery is sent to the warehouse, there’s an expiration tag applied to the outside of the shipping container. Make sure you’re not installing a battery that’s due to return to the manufacturer to receive an updated charge and testing procedure.
      A word about handling HV batteries, whether they’re new or remanufactured: These batteries are heavy! They’re packaged in clamshell cases to minimize the risk of electrical shock. Because of their weight, HV batteries should be stored low to the ground, and counter pros (and customers) should take great care when lifting them, to avoid injury.
      Let’s discuss a few add-on sales opportunities. I firmly believe that all shops working on electric vehicles need high-voltage gloves, insulated handtool sets and a Level 2 charger. Remember, all EVs use electrons the entire time they’re in a shop – as opposed to ICE vehicles, which only use gasoline when the engine is running.
      Advanced diagnostic tools represent another great sales opportunity. When it comes to diagnosing EVs and their batteries, the current level of diagnostics only allows a technician to see what’s transmitted over the data bus lines of communication. This is because a traditional diagnostic scan tool gets its information from the OBD II connector located under the dash. Autel has addressed this challenge with its MaxiSYS MS909EV platform.
      With the MaxiSys MS909EV system, technicians can analyze an EV battery by plugging into the OBD II port or connecting directly to the battery. By connecting to the BMS, technicians now have full insight into battery state of health and individual battery-cell state of charge; access to all the thermistors; and visibility into the “handshake” that occurs between a charger and the vehicle. The MS909EV screen displays detailed graphics and in-depth connection guidance to provide safe and secure testing, as well as comprehensive diagrams of high-voltage system blocks, components and sockets. In addition to providing rapid analysis of high-voltage systems in electric and hybrid vehicles, the MS909EV’s intelligent diagnostic capabilities extend to U.S., European and Asian gasoline and diesel vehicles.
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    • By Counterman
      The VVT category continues to grow in the automotive aftermarket. These systems are becoming more and more common as manufacturers try to meet tightened fuel-economy standards. When it comes to meeting those standards, variable-valve timing (VVT) is just one piece of the puzzle. As these vehicles exit the factory warranty period, there’s a huge opportunity for counter pros to serve customers’ repair needs.
      Variable-valve timing is the process of altering the timing and/or duration of a valve lift event, to improve performance, fuel economy and emissions.
      On a conventional engine, the opening and closing of the valves is based on their fixed position relative to the timing chain or belt, which is driven by the crankshaft. Without VVT, the valve timing remains the same for all conditions. This means that certain compromises must be made by manufacturers; this is achieved by selecting a specific cam profile. The cam profile affects the valve lift and duration.
      However, an engine equipped with VVT can make additional adjustments, so it isn’t constrained by the cam profile. VVT systems allow for improved performance over a broader operating range. The ability to alter valve timing at any engine speed gives manufacturers the ability to tune for optimal performance and efficiency. The camshaft’s timing can be advanced to produce better low-end torque, or it can be retarded to have better high-end torque as directed by the ECU.
      System Overview
      It’s important to point out that VVT is not just a single part or component – it’s an entire system. There are a number of components that all need to work hand-in-hand in order for the system to function. Let’s talk about some of the components that make up the entire system.
      The part that actually controls the position of the camshaft is the phaser. Cam phasers may feature a piston-type construction, or a vane-type construction. Regardless of construction, they use engine-oil pressure to push against a strong internal spring. A VVT solenoid is used to adjust the engine-oil pressure into the phaser.
      While early VVT systems were active only in higher rpm ranges or under specific conditions, modern systems are actively adjusting the intake and exhaust camshaft positions for the best possible efficiency at all times.
      VVT systems have caused one emissions system to become all but extinct: exhaust-gas recirculation (EGR). Since VVT is able to control the way gasses enter and exit the combustion chamber, there’s no need for EGR systems.
      EGR systems were designed to reduce nitrous oxides (NOx) by recirculating exhaust gasses back into the intake manifold. This causes the combustion temperature to drop below 2,500 F, preventing the formation of these harmful gasses. EGR systems did work, but lacked the reaction time and precision offered by VVT systems.
      Failure Points
      In many ways, engine oil is the lifeblood of the VVT system. Inadequate oil pressure or contaminated oil will hamper system performance. It’s very important that customers are following the manufacturer’s maintenance schedule, and using only the specified type, grade and viscosity of engine oil in their vehicle.
      Clean engine oil is critical to VVT-system operation. The oil passages of a VVT system are like a dead end, and the oil doesn’t flush out the passages all the time. If a piece of debris finds its way into a phaser or oil-control valve, it could be there for a while. Most manufacturers use a metal-screen filter to prevent debris from reaching the variable-valve timing system. Some manufacturers make the screen serviceable but, on some vehicles, it could be inside the oil-control solenoid and almost impossible to inspect or even clean.
      The relationship between the camshaft and crankshaft is critical in today’s VVT systems. The ECU relies on information from the camshaft position sensor and the crankshaft position sensor to determine ignition and valve timing. If either of these sensors produces a faulty signal, the VVT-system performance will suffer. A loose or stretched timing chain or timing belt, or a worn timing guide or tensioner, all could negatively affect the VVT system.
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    • By Counterman
      Camshafts are one of those components that can define an engine. Cams can have a direct effect on the efficiency, power curve, sound and even attitude of the engines they are installed into. Muscle cars and race cars are two examples of vehicles that are immediately recognizable by a loping, rumbling idle that builds into a deafening roar as they’re pushed harder and higher through their rpm range. 
      A “stock” camshaft usually is designed as a compromise between performance and drivability, with considerations for emissions and fuel economy, while performance cams trade much of the “politeness” of a stock camshaft in favor of brute horsepower. 
      If you were to open any of the major speed catalogs (or look up the information on their website), you’ll discover three things: Performance parts aren’t cheap; there are a LOT of cams to choose from; and each one is accompanied by a list of specifications including duration, lift, lobe separation and recommended rpm range/usage. But what makes one cam any different from another, and what do some of the terms used to describe a performance cam actually mean?
      Duration refers to the amount of time (expressed in degrees of crank rotation) that an intake or exhaust valve is “off” of its seat. This equates to the amount of time the valve is open, allowing air to enter or exhaust to escape. Generally, a longer duration means a “deeper breath” (or exhalation), although the amount of overall airflow through the cylinder is also affected by “lift.”
      Lift, or more specifically, “valve lift,” is the distance the valve travels as a result of the action of the camshaft. As the cam rotates on an overhead-valve (OHV) engine, the eccentric lobes act directly upon the lifter, raising it (and the pushrod above) a specified distance. The pushrod transfers this “lift” to a rocker arm, which in turn presses down on the valve, releasing it from its seat. Valve-spring pressure helps the valve close at the end of its cycle, and keeps the valvetrain components from clattering as they return to a resting position.
      In an overhead-cam (OHC) design, the cam lobe contacts the rocker arm directly, or against the valve itself when paired with a “bucket tappet,” which protects the valve stem from wear. The design of a rocker arm also multiplies the lift imparted by the cam lobe, creating more lift at the valve than at the lobe. Performance rocker arms use this advantage to improve lift without altering the existing cam profile.
      Us old-timers sometimes refer to camshafts as “bump-sticks,” as they seem to have lobes poking out in every direction. They are, however, precisely engineered to open and close multiple valves in a perfectly timed sequence to maximize their effectiveness. Lobe-separation angle (LSA) is a fancy name for the distance (again in degrees) between the centerlines of the exhaust and intake lobes on a shaft. This distance, along with the duration of the cam, will determine the amount of “overlap” in the movement of the intake and exhaust valves.
      Let’s look at a “racing” cam, and how its design affects performance. Intake valves open slightly before the engine begins pulling in air on the intake stroke. Call it a “head start,” but it helps promote airflow through the cylinder. As the piston reaches the bottom of its stroke, the intake valve is still open – pulling as much air as it can into the cylinder – then closes as the piston begins compression. Exhaust valves also open a bit before the power stroke is completed, with the pressure of the expanding gas helping “push” the spent exhaust out of the cylinder.
      With both valves slightly open at top dead center, more cool air is drawn in as the hot exhaust is expelled. This phenomenon is called “scavenging,” and at higher rpm can further boost horsepower. The smaller the separation between lobes (and the more duration) the more overlap will occur. Unfortunately, at idle and low rpm, it also causes a lumpy rumble, low engine vacuum and a lack of low-end power. Although many people (myself included) enjoy hearing this signature sound at the race track, it isn’t very useful in a daily driver! Choosing the right camshaft for your intended purposes begins with defining your intended purposes!
      Every camshaft design has a “sweet spot” – the rpm range at which it performs the best. Camshaft manufacturers’ rpm recommendations are a result of dyno-testing the unique combination of lift, duration, lobe design and separation engineered into each particular grind profile. If you aren’t going to be consistently operating in a cam’s specified rpm range, it may not be the best choice for your project. Your mostly stock, daily driven street vehicle won’t benefit much from a race-ready cam that really needs to rev up around 5,000 rpm to make maximum power. As with any other performance-part purchase, it pays to do your research before buying … no matter how cool the stickers will look on your toolbox!
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    • By Counterman
      AAPEX is accepting nominations for the third-annual Service and Repair Awards for Shop Owner of the Year, Service Advisor of the Year and Technician of the Year.
      The awards will honor service and repair professionals who have performed above and beyond in 2022 and who demonstrate a commitment to training, as well as community, charitable and industry involvement.
      Nominations are due by Wednesday, Aug. 31, and should be submitted using the online AAPEX Service and Repair Awards nomination forms on the event’s
      link hidden, please login to view. Judging will be conducted by an independent panel of shop owners. Recipients of the three prestigious awards will be recognized and honored on Tuesday, Nov. 1, during the AAPEX keynote session.

      The AAPEX Service and Repair Awards were established in 2020 to recognize and elevate the essential services provided by shop owners, service advisors and technicians to keep the motoring public on the road, even during challenging times.

      In 2021, AAPEX award recipients were:
      Shop Owner of the Year – Jamie and Eric Carlson, Ervine’s Auto Repair & Grand Rapids Hybrid and EV Service Advisor of the Year – Brittany Schindler, Rod’s Japanese Auto Care Technician of the Year – Matt Fanslow, Riverside Automotive

      AAPEX 2022 will take place Tuesday, Nov. 1, through Thursday, Nov. 3, at The Venetian Expo in Las Vegas.
      AAPEX represents the more than $1.6 trillion global automotive aftermarket. Historically, the event draws approximately 2,500 exhibiting companies that display innovative products, services and technologies that keep the world’s 1.3 billion vehicles on the road. AAPEX is a trade-only event and is closed to the general public.
      AAPEX is co-owned by the Auto Care Association and the Automotive Aftermarket Suppliers
      link hidden, please login to viewAssociation (AASA), the light-vehicle aftermarket division of the Motor & Equipment Manufacturers Association (MEMA). For more information, visit  link hidden, please login to view or e-mail [email protected] On social media, follow AAPEX at #AAPEX22. The post
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      DIY like a pro! Shop from over 1,000,000 Repair Manuals at eManualOnline.com! As low as $14.99 per manual. Shop now.


      DIY like a pro! Shop from over 1,000,000 Repair Manuals at eManualOnline.com! As low as $14.99 per manual. Shop now.

    • By Counterman
      The cooling system no longer is focused on cooling as much as it is on managing and maintaining a consistent engine and transmission temperature. Since our industry always seems to find a way to inundate us with new acronyms and terminology with every model year, it could be only a matter of time before they start to call it a Powertrain Heat-Management System (PHMS).
      Make no mistake: The name is not real – at least not yet. I just made it up. But it’s a very accurate representation of what a modern-day cooling system does. To understand the technology of today’s cooling system and why the name almost deserves a change, let’s first look at a brief history mixed with a touch of science.
      The term “cooling system” originally came about on the early automobile, and that’s exactly what they did. However, the early cooling systems were … simple. Scientifically known as “thermosyphon systems,” the hot coolant in the engine rose upward into the top tank of the radiator. As it cooled, it fell to the bottom of the radiator, where it then would flow into the engine block. The result was a continuous circulation of coolant through the engine, requiring no water pump or thermostat to make it work.
      Although the early cooling system worked well, it had no choice but to evolve, as engines got bigger and became more powerful. If you think about an engine on a scientific basis, it’s nothing more than a way to convert heat energy into mechanical energy. Basic logic tells us that the more power an engine produces, the more heat is generated that must be removed.
      Since cooling systems needed the ability to remove more heat, they quickly evolved into utilizing water pumps and thermostats. Thermostats always have had two purposes. First, the engine coolant must remain in the radiator long enough to transfer its heat to the air. When the thermostat is closed, it allows sufficient time for this to occur, and when it opens, the coolant flows into the engine and is able to absorb heat to begin another cycle.
      Second, engines need to operate near the boiling point of water. Why? Because water is a byproduct of combustion, and this high operating temperature ensures that water is evaporated from the engine oil during operation. Without the thermostat set to keep things hot, the engine oil cannot burn off water and will quickly become contaminated.
      Cooling systems, even as we entered the era of fuel injection and electronic management, remained fairly simple at first. But we knew that engine temperature was directly related to fuel economy, emissions and power output, and that maintaining that temperature where we wanted it was a necessary step to achieve our goals in those areas.
      It didn’t take long before the need for precise engine-temperature control became a prevailing factor affecting both engine and cooling-system design. Many components that we thought would never change began to receive a full dose of technology. Here’s a look at how things are shaping up for the future.
      Thermostats
      While not an everyday item yet, electrically controlled thermostats are being utilized in some applications, and I expect we’ll see an increase in this. The ability of an internal-combustion engine to achieve maximum fuel economy, minimum emissions and maximum power occurs at slightly different temperatures for different operating conditions. By adding this additional level of precision to temperature control, we can match temperatures to operating conditions, increasing power output and fuel economy.
      This need for precise temperature control is why modern fuel-management systems monitor coolant temperature and if there is any deviation outside of the expected norm, a very common diagnostic trouble code (DTC) is P0128 (“Engine Coolant Below Regulating Temperature”). As time goes on, we can only expect this to become a parameter that’s much more closely monitored.
      To further illustrate the advantage of an electronically controlled thermostat, consider traditional (old-school) thermostat operation. As the engine warms up, the radiator and hoses remain cold. When monitoring cooling-system performance as a technician, it’s common to keep a hand wrapped around the upper radiator hose. It stays cold until the thermostat opens; then it gets hot really quickly as the coolant flows from the engine into the radiator.
      Then we use our hands to feel the radiator tanks warming up, and when they do, we then expect that the electric cooling fans (if equipped) are due to come on within a few moments, and we often move our hand into the path of the air coming off of the cooling fan to sense the volume of airflow and amount of heat being drawn off the radiator. Hi-tech is watching the engine temperature on a scan tool while this happens.
      The point of this? The overall process of heat transfer is slow, and extreme precision is not possible with a traditional thermostat. As a result, the most advanced engine-management systems are looking ahead at engine temperature based on throttle position and calculated load, so that they can precisely manage engine cylinder and head temperature, effectively managing combustion efficiency. It’s impressive. Electronics and electronic thermostats make it all possible.
      Water Pumps
      What could possibly change about water pumps? That’s what I used to think, but they are changing. As effective as a traditional belt-drive water pump always has been, if we look at them from an old-school operational standpoint, as we did thermostats, we begin to see the flaws in their operation. Traditional belt-drive water pumps run the whole time at the speed of the engine, but with modern temperature-management technology, it’s not necessary for them to run constantly. Not only does this create an unnecessary drag on the engine, but it also can reduce the accuracy of precise temperature control.
      By redesigning the traditional water pump and adding electric water pumps into the system, unnecessary drag is eliminated, and the engine-management system is able to generate coolant flow when needed, as needed. This can help reduce warmup time and also improve overall temperature control.
      Electric water pumps also have the advantage of remote locations in engine compartments, which is beneficial as space becomes more and more constricted, and they are utilized for after-run features to help cool components such as turbochargers.
      Cooling Fans
      Electric cooling fans are not new by any means, but they no longer are a simple on-or-off type of fan. Early fans often employed a resistor to create both a low- and high-speed option, but many of today’s fans are pulse-modulated variable-speed fans that again give the engine-control module the ability to match fan speed with other operating conditions.
      Active Grille Shutters
      The newest member of the cooling-system technology family is the active grille shutter. Many manufacturers are utilizing this technology on certain vehicles, which, as you might have guessed, looks just like a set of shutters over some portions of the radiator. This can improve vehicle aerodynamics as well as decrease warmup times. They only open when needed to allow for additional cooling.
      Heater Cores
      Heater cores are part of the cooling system. Even though they don’t generally affect system function in the terms of engine-temperature management, inadequate heat stemming from a restricted heater core is a common complaint. But a restricted heater core is sometimes misdiagnosed as a bad thermostat or vice versa. And some vehicles utilize an electric water pump specifically to move coolant through the heater core. If the pump is bad, it could be misdiagnosed as a restricted heater core. Cooling-system diagnosis always should take into account the ever-increasing complexity of HVAC systems.
      Electric Vehicles
      Just when you thought there couldn’t be any more, hybrid and electric vehicles are bringing additional changes. Did you ever think you would see a high-temperature radiator and a low-temperature radiator? Plus, a water-cooled air-conditioning condenser? You’ll start to see them on electric vehicles.
      You also can throw in some valving and a high-voltage coolant heater to boost heater-core output, plus a completely different cooling circuit for the batteries, power inverter, transaxle and electric motor. The good news for us? There’s a lot more to fix and a lot more parts to sell.
      So, when will they start to call it a PHMS? And I’m waiting for the day of GPS-monitored temperature-sensing microchips that float around the cooling system, reporting the exact temperature of the coolant along the way. Sound crazy? Probably. But if it ever happens, just remember where you heard it first.
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