Undercar: Diagnosing And Repairing Wheel Bearing Noise
by Ed Sunkin
As you begin your career in the auto service industry, youll find that for the most part, the internal combustion engine (ICE) which has been around for more than 100 years hasnt changed much in theory. However, there have been many internal modifications to the ICEs design that has made it more fuel efficient in recent years, as the world tries to reduce its thirst for oil. To become a knowledgeable diagnostic technician, youll need to become familiar with these technologies and understand how to service them when a problem arises.
By Ed Sunkin
Blasts from the Past
There are two engine technologies that have been around for years and are now generating a resurgence of interest. You see, these days, automakers are looking to create better fuel efficiency, without sacrificing power. So engineers have dusted off blueprints for direct injection for gasoline engines and turbocharging systems and have begun incorporating them into the ICE design.
Direct injection for gasoline engines is where fuel is injected right into the combustion chamber of each cylinder, as opposed to conventional multi-point fuel injection that occurs in the intake manifold. Turbocharging is where an exhaust gas-driven compressor is used to increase the power output of the engine by compressing air that is entering the engine, thereby increasing the amount of available oxygen.
Gasoline direct injection (GDI) engines are seeing a recent resurgence due to their increased fuel efficiency and high power output. In the late 1990s, there were high hopes for GDI when Mitsubishi Motor Corp. introduced its patented GDI system for a handful of models in Japan. And in March 2000, following the European launch of the Siemens Automotive High-Pressure Direct Injection (HPDI) system for the Renault Megane Cabriolet models, many in the industry thought there would be an instant market boon for this technology. However, in the past five years, the technology seemed to be limited to a handful of vehicles on the road today but all of that is changing, as we saw recently at the North American International Auto Show in Detroit.
Cadillacs 3.6L Direct Injection Engine
General Motors engineers claim that its 2008 Cadillac CTS has been painstakingly designed and engineered to unite luxury sedan poise and sports car performance. The 2008 Cadillac CTS features GMs new 3.6L direct-injection V6 VVT engine, (shown here) delivering an estimated 300 horsepower and 270 lb.-ft. of torque. This new powerplant is a compelling mixture of power, smoothness, efficiency and technical sophistication.
This engine will be the top-level option for the 2008 CTS, joining the existing 2.8L V6 and 3.6L V6. Designed to operate with regular unleaded gasoline, the new 3.6L direct-injection V6 produces power similar to many V8 engines, but with much better fuel economy.
GM said that the application of gasoline direct-injection technology on the 3.6L VVT engine contributes greatly to a 15% increase in horsepower; 8% increase in torque, and 3% improvement in brake-specific fuel consumption. Additionally, the application of direct injection reduces cold-start hydrocarbon emissions by 25%.
Getting More Kick from Soccer Mom Minivans
Proven powertrains like a 3.3L V6 engine that can be fueled with alternative fuel E85 and new options like a 4.0L V6 engine that produces 240 hp and 253 lb.-ft. of torque give drivers plenty of choices in the new 2008 Chrysler Group minivans.
Although adding a 4.0L, V6 aluminum engine to its lineup, the biggest improvement for Chryslers minivans are the powertrains. Chrysler Group is the first to offer a six-speed transaxle in a minivan, said Larry Lyons, vice president of Chrysler Groups front-wheel-drive product team. With a new 4.0 V6 aluminum engine and new six-speed transaxle, the 2008 Chrysler and Dodge minivans offer added performance and a smoother driving experience.
In North America, three powertrains offer performance and value for a variety of minivan uses. The 3.3L V6 flex-fuel-capable engine is mated to a four-speed transaxle and produces 170 hp and 205 lb.-ft. of torque. The 3.8L V6 engine is mated to a new six-speed automatic transaxle that produces 198 hp and 230 lb.-ft. of torque.
And the new 4.0L V6 is mated to the new six-speed automatic transaxle that produces 240 hp and 253 lb.-ft. of torque.
Chrysler engineers said other engine design improvements for the 4.0L engine include sequential multi-port electronic fuel injection, electronic throttle control, platinum-tip spark plugs and a wide-band detonation sensor system to allow operation on regular or mid-grade fuels from 85 to 89 octane.
The Dodge Grand Caravan and Chrysler Town & Countrys new six-speed automatic transaxle is derived from the Chrysler Groups proven four-speed transaxle. Building on the capability of Chryslers four-speed automatic transaxle, the six-speed automatic transaxle adds two new primary gear ratios and a secondary ratio for optimized passing performance at highway speeds. The gear ratios of the six-speed transaxle allow the engine to work more efficiently at lower speeds, providing a pleasant driving experience.
Part and process commonization allowed Chrysler Group engineers to develop the six-speed transaxle in a shorter period of time and at a lower investment cost than previous transaxles without sacrificing durability or quality.
The six-speed transaxles higher numerical first gear launches the minivan more briskly than a four- or five-speed transaxle. It also provides smaller steps between ratios, which means the engine speed changes less with each shift and makes the shifts feel smoother. The six-speed transaxle also engages a more appropriate ratio for any driving situation. In particular, wide-open throttle kick-down shifts to fourth gear engage at a slightly higher ratio than do upshifts to provide needed acceleration with less engine flare.
MINI Cooper S Gets a Major Boost
The 2007 MINI Cooper S is powered by a brand-new 1.6L turbocharged engine developing maximum output of 172 hp. This superior power is provided by a twin-scroll turbocharger driven by the separate flow of exhaust gases coming out of two cylinders on each side.
This configuration enables the turbocharger to build up its extra power and boost with virtually no delay even from low engine speeds. And the effect achieved in this way is most significant, the 1.6L four-cylinder power unit of the MINI Cooper S developing its power and performance in a style quite exceptional for an engine of this size: Maximum torque of 177 lb.-ft. is maintained consistently between 1,600 and 5,000 rpm, and when accelerating, all-out torque is raised to an even higher peak of 192 lb.-ft. by a brief increase in charge pressure (overboost).
On the other hand, variable valve management technology highlights the power unit of the MINI Coopers 1.6L, four-cylinder, normal-aspired engine, providing a maximum output of 118 hp, and peak torque of 114 lb.-ft. The MINI Cooper 1.6Ls intake valve timing incorporates advanced control and management based on the BMW Groups VALVETRONIC technology, and is naturally fully variable, with valve lift and opening times being adjusted infinitely and with electronic precision to the drivers current requirements in terms of power and performance.
This innovative valve management ensures not only a very smooth and dynamic response as well as supreme motoring culture, but also low fuel consumption and optimized emission control at all times. Both engine variants for the 2007 MINIs are fitted crosswise at the front and convey their power to the front wheels. Composite instead of conventional cast camshafts and a weight-optimized crankshaft are part of the lightweight concept of the all-aluminum power units. Fuel consumption, in turn, is optimized by a volume flow-controlled oil pump and an electronically controlled water pump for the coolant circuit two technical features so far only to be found in larger and more expensive model segments.
Fords Future Powerplants
Unveiled at the North American International Auto Show, the Lincoln MKR concept introduced new engine technology that delivers V8 power and performance with V6 fuel economy. Ford engineers said the engine technology, named TwinForce, will appear on future Lincoln and Ford vehicles.
Ford engineers explained that TwinForce uses both direct injection technology and turbocharging technologies common in diesel engines, but have only recently been combined for use in gasoline engines.
Ford designers said TwinForces direct-injection fuel system can more precisely control when and how much fuel is injected into the engine cylinders, allowing for more efficient burn and improved combustion control that delivers optimal performance and fuel economy.
Fords new Duratec 3.5L all-aluminum V6, recently named one of the 10 Best Engines by Wards, was the foundation for the TwinForce technology.
The Lincoln MKRs engine is flex-fuel capable, providing the driver with the flexibility to switch back and forth between gasoline and E-85 ethanol. Flexible fuel is an important step toward development of more efficient, renewable biofuels that can provide energy security as well as environmental benefits.
Combining the high octane found in E-85 or premium gasoline with TwinForce technology allows the Lincoln MKRs V6 to deliver 415 hp and 400 lb.-ft. of torque an impressive 118 hp/liter. Ford engineers explained that to achieve this type of performance from a V8 would require an engine displacement of 6.0L or larger. As a result of the smaller V6, the Lincoln MKR concept delivers 15% better fuel economy than a V8 with similar performance.
The TwinForce technology used in the Lincoln MKR represents Fords first application of direct injection on a V6 engine.
In the U.S., the market appears to be ready for the new TwinForce technology. Ford said it already has several direct-injection equipped four-cylinder engines in production, including a 1.8L launched in the 2003 Ford Mondeo and the 2.3L turbocharged engine developed by Mazda for the 2006 MazdaSpeed6.
A Luxury Sedan with V10 Powerplant
Audis S8 vehicle is equipped with a new V10 FSI engine that delivers 450 hp at 7,000 rpm and 398 lb.-ft. of torque the latter available from just 3,500 rpm from a capacity of 5.2L. As on the Le Mans winning R8, the most successful racing car in the world, this improved FSI gasoline direct injection assures superior power output in the Audi S8.
Audis engineers claim this luxury sedan sprints from 0 to 60 in 4.9 seconds, though its electronically governed to a top speed of 155 mph. Audi engineers also said the combination of 10 cylinders and FSI technology gives Audi a unique position in the market. A 10-cylinder engine is the ideal power plant for realizing sporting aspirations. It has the edge on a comparable 12-cylinder unit thanks to the smaller number of components, resulting in lower moving masses and less internal friction; the fuel is consequently put to very efficient use. A V10 is moreover considerably lighter and more compact than a conventional 12-cylinder engine including all its add-on components, according to the Audi press release.
The engine in the Audi S8 is just 26.9 long, 31.5 wide and 28.0 tall. The bare engine measures 22.0 in length.
Audi engineers explained that although an eight-cylinder engine would be even more compact, to make it into the 5L class it would need large, heavy pistons and connecting rods, so its ability to rev freely would be impaired as a result. It is no coincidence that many competitors have generally concentrated simply on high torque with their large capacity V8 engines, rather than attempting to squeeze sporty performance out of them too.
The 450 hp V10 in the Audi S8 belongs to the next generation of Audi V-engines, all of which have a 90 included angle and a spacing of 90 mm between cylinder centers. Its two banks of cylinders are offset by 18.5 mm. The bore measures 84.5 mm, stroke is 92.8 mm, and its displacement is 5,204 cc. Engineers explained that the crankcase of the Audi 10-cylinder engine is produced by low-pressure die-casting, from a hypereutectic aluminum alloy. This technology renders separate cylinder liners superfluous; the liners are instead honed directly from the material by exposing the hard silicon crystals. And a so-called bedplate design an intermediate frame gives the crankcase extremely high torsional rigidity and improves its vibrational behavior. The cast-in grey cast iron bearing bridges reduce the thermal expansion of the aluminum casing while they simultaneously keep the amount of play at the main crankshaft bearings within tight tolerances. The connecting rods are produced forged from steel, and the pistons from an aluminum alloy.
With its crankpin offset of 18, the V10 fires at the ideal spacing of 72 crankshaft angle. A balancing shaft located within the V eliminates the free inertial forces of the first degree and also contributes toward the engines notable refinement.
All four camshafts of the 10-cylinder engine can be adjusted continuously by 42 crankshaft angle via hydraulic camshaft adjusters, depending on the load and engine speed, to modify the valve opening overlap. They thus optimize filling of the combustion chambers and improve engine response.
Engine designers allowed the camshafts complete with the balancing shaft, the oil and water pump and the auxiliaries to be driven by maintenance-free chains running on the reverse side of the engine. They actuate the 40 valves via roller cam followers with hydraulic valve-play compensation. The diameter of the valves on the intake side is 32.5 mm, and 28.0 mm on the exhaust valves. The exhaust valves are sodium-filled, for a cooling effect.
The V10s gasoline direct injection permits a high compression ratio of 12.5:1 and a correspondingly effective combustion process based on a homogeneous lambda value of 1.
Mitsubishis All-New Engine Architecture
The 2008 Lancer 2.0L engine is based on an all-new architecture that employs new technologies and weight-reducing features. The new aluminum cylinder block will also be used as the foundation for the next Lancer Evolution engine. The cylinder head is also aluminum.
Mitsubishi engineers said the double overhead-cam (DOHC) cylinder head features four valves per cylinder, compared to the single overhead cam (SOHC) configuration used before. And the Mitsubishi Innovative Valve Timing Electronic Control (MIVEC) a continuously variable valve timing system ensures optimal power, high fuel efficiency and low emissions across the engines operating range. The Lancers MIVEC system works on both the intake and exhaust valves.
The 2.0L engines bore and stroke both measure 86.0 mm, which engineers refer to as square. In contrast, the previous-generation Lancer 2.0L engine was a long stroke (or under-square) design, with bore measuring 81.5 mm and stroke 95.8 mm.
The new cylinder dimensions contribute to a free-revving character (6,500 rpm redline) and an optimal balance of linear power delivery and wide torque curve that gives the Lancer responsive characteristics of a larger-displacement engine.
For example, by 2,500 rpm the new Lancer 2.0L engine is already producing as much torque as the previous engine did at its peak at 4,250 rpm, in large part thanks to the MIVEC system. The strong mid-range torque in the Lancer will make the car feel more responsive in everyday driving.
The Lancer 2.0L MIVEC engine also has a higher compression ratio (10:1 vs. 9.5:1 for the previous engine) and still uses regular-grade fuel (87 AKI). Using a timing chain instead of a belt allows for a more compact design and also helps ensure reliability. Iridium spark plugs contribute to lower emissions and help extend major service intervals for lower cost of ownership. The California PZEV-certified models use an exhaust gas recirculation (EGR) system.
The new Lancer engine uses a number of weight-saving features and technologies chief among them the new aluminum cylinder block and head. Overall engine weight has been reduced by 59.5 lbs. from the previous-generation, iron-block Lancer 2.0L engine.
Other weight-reducing measures include a plastic cam cover and intake manifold and double-layer stainless steel exhaust manifold. The exhaust manifold has a rear location on the transverse engine, compared to the front location for the previous engine, yielding important benefits. The rear location makes it easier to package the catalysts for quicker light off, and therefore better emissions performance.
Maserati Serves Up a 400 HP V8
Consider yourself more of a performance enthusiast? Heres a peak at Maseratis trademark V8 engine for 2007. The 90, 4.2L, V8 engine is called both light and compact by its engineers, delivers prompt and progressive power of 400 hp at 7,000 rpm, equal to a specific power of 95.2 hp/liter.
Distribution is by four overhead camshafts, two per bank, chain driven, with four valves per cylinder that are controlled by hydraulic tappets. The aspirated camshafts, with a continuous-phase, high-pressure speed gear-change, have a characteristic profile that optimizes power delivery even at low engine speeds. The accelerator is Drive by Wire, electronically controlled, meaning theres no mechanical linkages. While having the same maximum power, the V8 has different technical features and set-up depending on the vehicle version:
Quattroporte Automatic: with its distinct Maserati blue engine heads (shown here), stressing soft and fluid driving with a maximum torque of 339 lb.-ft. at 4,250 rpm, 75% of which is available at 2,500 rpm with a maximum speed of 165 mph.
Quattroporte DuoSelect: V8 red heads and dry-plate clutch lubrication; a technical solution on a par with the most advanced racing engines, with a maximum speed of 171 mph.