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


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    • By Mighty Auto Parts
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      link hidden, please login to view appeared first on link hidden, please login to view. Neglecting maintenance intervals can result in performance issues and internal engine damage due to sludge deposits restricting the flow of lubricant to vital engine components. Evidence of lack of maintenance will normally show up in the oil filter and related housing. The filter media will be impacted with sludge deposits. Where applicable, the filter cap […]
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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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