3100 Yearly changes
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3100 Yearly Changes & Updates
Overview
Built at the world's largest automotive engine assembly site in Tonawanda , N.Y. , the 3100 V6 was developed as a V6, rather than a shortened V-8. The 3100 has been improved annually to enhance fuel economy and durability and to meet increasingly stringent emissions mandates. It remains one of GM’s most popular V6 engines because it satisfies customers who appreciate fuel economy and low cost of ownership, and still delivers the power for good vehicle performance. As of the 2005 Model Year the 3100 LG8 V6 is used exclusively in the Buick Century. With steady application of advanced technologies and improvements in noise, vibration and harshness control, the 3100 V6 continues to deliver solid performance for buyers who emphasize value and low cost of ownership.
2000 Model Year
In model year 2000, new Multec II fuel injectors improved fuel efficiency by making fuel delivery more precise, and reduced the likelihood of injector clogging. A number of enhancements reduced internal engine friction, in turn reducing noise and improving fuel economy. The 3100 was also equipped with a high-flow intake manifold and cylinder heads developed for the 3400 LA1 3.4L V6
2001 Model Year
Summary of changes for the 2001 Model Year
- More Efficient Catalytic Converters
- Air Gap Downpipe
- Intake Valley Baffle
- Modified Lifter Guide
- More Durable Water Pump
- Improved Bearings for Accessory Drive Belt Tensioner and Idler
- High-Resistance Spark Plugs and Wires
- Plastic Fuel Tank
- Revised Throttle Body
- New Starter Motor
- Sleeveless Coolant Sensor
Detailed Descriptions
Better Catalysts
Improved technology increases the catalytic converter's efficiency, allowing National Low Emissions Vehicle (NLEV) certification with considerably less catalyst volume and lower cost. Improved production methods allow a new catalytic coating and thin-wall catalyst substrate--the source of the catalytic reaction that turns exhaust emissions to harmless vapor. These production techniques mean improved performance with less platinum, palladium and other precious metals in the converter. Converter volume has been reduced from 163 ci to 116 ci.
Air Gap Downpipe
An Air gap downpipe connecting the exhaust manifolds with the catalytic converter, used on engines for California and select Northeast states for model year 2000, is applied to all LG8s. The pipe has dual walls separated by a jacket of air, and heats more quickly than conventional single-wall steel pipe. Combined with more efficient catalysts and a new Denso oxygen sensor with a 6.6-watt heating element, the Air Gap Downpipe speeds emissions light-off by as much as five seconds. As a result, most LG8s need no Air Injection Reaction (AIR) for National Low Emissions Vehicle (NLEV) certification. Eliminating the AIR system eliminates assembly parts and reduces cost.
Valley Baffle
A baffle in the intake manifold valley protects the manifold gaskets from direct contact with engine oil, reducing the likelihood that the gaskets can saturate with oil.
Lifter Guide
Valve lifters are now pre-assembled with the lifter guide, removing a step from the engine assembly operation and improving efficiency. Further, each guide is fitted with a plastic shield that, with the new intake manifold valley baffle, virtually eliminates the possibility that manifold gaskets can be exposed to oil. This protection removes a potential leak source.
Water pump Assembly
The seal on the water pump shaft is made of more durable hard carbon silicon carbide. Further, the pulley bearings are sealed. Together, the improvements extend the water pump's useful life and reduce the potential for leaks.
Drive Belt Tensioner
Bearings in the accessory belt tensioner and idler, which maintain proper belt tension without adjustment, are now validated to 150,000 miles of service. The permanent lube in the bearing maintains its lubricating properties longer. Further, the bearing seal is improved to keep the lubricant in and water, dirt and other contaminants out.
Improved Plugs and Wires
New high-resistance spark plugs and wires virtually eliminate the possibility of radio interference. The plug wires are soldered rather than snap-fit at the connector inside the plug boot. Soldering improves reliability and decreases assembly errors by reducing the possibility that the plug wire can inadvertently be detached from the connector. Finally, the Delphi spark plugs have silicon coated platinum tips to reduce fouling and the likelihood of service over the 100,000-mile plug life. The coating is particularly useful during post-production marshalling, when cars are started frequently and run briefly, and reduces the likelihood of pre-delivery plug cleaning at dealerships.
Fuel Tank and Canister
Pontiac Grand Prixs with LG8 engines are equipped with a plastic fuel tank for model year 2001. The 2001 Grand Prix is equipped with a new 2.1-liter evaporative canister for its on-Road Vapor Recovery (ORVR) system.
Revised Throttle body
A new throttle body spring lightens accelerator pedal feel. A hole in the throttle blade has been eliminated, reducing the minimum Airflow rate and allowing a lower engine idle speed.
Starter
The new starter motor, supplied by Delco Remy America, draws less amperage than the starter used for model year 2000, yet delivers the same cold cranking power. That means the same starting power with less drain on the battery. The new starter is also lighter and costs less to manufacture.
Sleeveless Coolant Sensor
LG8s for the Malibu are equipped with a new coolant temperature sensor. The sensor uses a plastic insulator to protect electrical leads inside the brass housing, rather than a rubber sleeve, and reduces the possibility of assembly rejection or shorting in operation.
Continuing Features
In 2000, new Multec II fuel injectors improved fuel efficiency by making fuel delivery more precise, and reduced the likelihood of injector clogging. Fuel pressure was increased from 300 to 380 KPa for improved hot starting. A number of enhancements reduced internal engine friction, in turn reducing noise and improving fuel economy. Those included reduced friction piston rings, revised cam profiles, and a new cam gear and drive chain. The 3100 was fitted with a high-flow intake manifold and cylinder heads developed for the LA1 3.4-liter V8.
The LG8 was developed as a V6, rather than a shortened V8. Its 60-degree cylinder-bank angle makes it inherently smoother than 90-degree V6 engines. "It's one of our bread-and-butter V6s, and we consider it a good value--a workhorse. It meets customer expectations for a base V6 at a reasonable cost." --Mike Parise, Model Year Manager, 60-degree V6 engines.
Leadership
The 3100 V6 continues to deliver solid performance, durability and economy with low cost of ownership. "A complete safety package requires on-demand zip for passing, merging into traffic and accident avoidance." --ROAD & TRACK 1999 BUYER'S GUIDE
2002 Model Year
For 2002, the cruise control module was improved with state-of-the-art electronic circuitry and a new control algorithm that updates itself every 30 seconds. New spark plug wires with 5000 ohms resistance reduced the likelihood of electromagnetic interference with AM band reception. In 2001, state-of-the-art technology increased the catalytic converter's efficiency, allowing National Low Emissions Vehicle (NLEV) certification with considerably less catalyst volume and lower cost.
2003 Model Year
Summary of changes for the 2003 model year
- Revised Crankshaft Bearing
- Revised Cylinder Heads
- Revised Pushrods
- Revised Camshaft Journal
- Water Pump
- Iridium Spark Plugs
- Maximum Oil Change Interval Extended
- Improved Starter Solenoid
Detailed Descriptions
Revised Crankshaft Bearing and Seals
The thrust bearing on the 3100 V6 (LG has been modified to optimize piston and bore oiling. The thrust bearing is fitted to the third main bearing cap to control the fore-aft movement of the crankshaft. The lower half of the bearing now has slots machined in a starburst pattern on its flange. Oil at the bearing cap is squeezed through the slots and forced in a fan pattern under the pistons and into the cylinder bore, providing another oil distribution path. This simple modification pays big dividends in improved internal lubrication and longer engine life.
Revised Cylinder Heads
The 3100 cylinder head castings are tapped with 8mm holes for the rocker arm bolts, reducing the tap size from 10mm, and the rocker arms are secured with 8mm bolts. This change commonizes machining for the 3.1L and 3.4L V6s (LA1) and increases assembly efficiency.
Revised Pushrods
Pushrods in the 3.1L are no longer heat-treated. The pushrod guides are now made of low friction nylon, rather than steel, and the pushrods no longer need heat-treating to limit wear.
Revised Camshaft Journal
The 3.1L front camshaft journal has been revised with a new timing pattern. This journal is now machined with 50/50 pattern of raised and lowered semi circles, rather than a single boss or lug. The operating principal for ignition and fuel injection timing has not changed, but the new timing pattern requires a slightly smaller cam sensor and modifications to the fuel injection wiring harness. The new timing pattern was introduced in anticipation of future development.
Water Pump
The 3100 water pump has a more efficient impeller design and the latest sealing technology, featuring a drip collector under the shaft. Most water pump seals are designed to release a few drops of coolant at a constant rate. With the drip collector, the drops are contained and evaporate. The drips are less likely to be mistaken for a leak.
Iridium Spark Plugs
The 3.1L benefits from the latest spark plug technology. The new plug has an iridium core in the conductor and same internal resistance. Iridium helps maintain spark density over the life of the plug. The tip is still coated with platinum, and the plug maintains a recommended life of 100,000 miles, yet the electrode design improves combustion efficiency for maximum fuel economy and minimum emissions.
Maximum Oil Change Interval Extended
New calibrations in the Powertrain Control Module (PCM) extend the oil-change interval in all vehicles equipped with the 3.1L engine. Engineers have adjusted the Oil Life System to account for widespread use of the new GF-3 motor oil. GF-3 (for “Gasoline Fueled, Standard 3") contains a friction modifier--an additive that makes the oil molecules more slippery. A new refining process leaves molecules in the base oil more stable. The oil degrades less with heat and retains proper lubricating properties longer.
Most oil change indicators work according to a predetermined mileage interval, which in turn is based on the oil’s anticipated life under some generalized operating cycle. In the 3.1L, the PCM records a number of variables, including engine speed, temperature, load or rpm variance, and period of operation at any given load and temperature. With this information, the Oil Life System calculates oil degradation and recommends an oil change when the oil is near the end of its useful life--in other words, when an oil change is actually needed. With the 2003 revisions, maximum oil change intervals have been increased approximately 20 percent. There is no upward limit on the interval. The owner’s manual in cars equipped with the 3100 V6 will continue to recommend an oil change at least once a year.
The benefits of the unlimited mileage interval, measured by customer convenience, maintenance cost or environmental impact, are obvious. The customer should never pay for an unnecessary oil change again. Using oil for its true useful life results in less petroleum consumed and less used motor oil to be recycled or disposed of.
Improved Starter Solenoid
The starter solenoid on all 3.1Ls has been improved to virtually eliminate the possibility of icing during cold-weather operation. Because of its typical location in most vehicles, the starter and its control solenoid can be exposed to moisture and ice during the winter. The solenoid's internal spool is now made of liquid crystal polymer (LCP), which does not absorb moisture. Further, the solenoid wire terminals have been redesigned in a tapered, round shape rather than a flat shape to reduce the possibility that moisture and ice can collect on them.
2004 Model Year
Summary of changes for the 2004 Model Year
- Graphite Head Gaskets
- Improved Water Pump
- Improved Sealing
- Improved Flywheel
- Changes for Common Assembly with 3500 High Value V6 (RPO LX9)
- Production shifts to Tonawanda, N.Y. engine plant
Detailed Descriptions
GRAPHITE CYLINDER HEAD GASKETS The 3100 V6 is now equipped with graphite head gaskets. The gaskets feature a layer of graphite applied over the perforated stainless steel core to enhance gasket durability and optimize performance over the life of the engine. The graphite improves performance at all temperatures and provides excellent sealing, compression recovery and coolant resistance. Moreover, the gaskets have a thicker flange than before to improve durability.
Water Pump
The 3100 V6's water pump has been redesigned to improve performance and durability. The impeller is thinner and lighter, and manufactured from stamped steel rather than cast iron. The impellor shaft is also thinner (12 mm compared to 15.9 mm). This reduces the size and surface area of the pump seal, reducing potential for seal leakage. Finally, the pump features a “weep reservoir,” or drip collector. Most water pump seals are designed to release a few drops of coolant at a constant rate. With the drip collector, the drops are contained and evaporate, and the drips are less likely to be mistaken for a leak.
Improved Sealing
Most gaskets on the 3100 V6 have been improved, including the head gaskets and water pump seal (above) and the intake manifold gaskets. The manifold gaskets are designed to reduce the chance of misalignment during assembly and improve build quality, and they have been optimized to prevent coolant seepage. Moreover, the gaskets have been redesigned with more durable seal materials and a dual sealing bead around the coolant crossover ports.
Improved Flywheel
The 3100's flywheel has been redesigned with an assembled retainer and a revised flex-hole design that doubles its rotary bending ability. The new flywheel is lighter than the previous part, and the new retainer increases assembly efficiency. Moreover, the flywheel is now common to both the 3400 LA1 V6 and the new 3500 LX9 High Value V6.
Changes for Common Assembly with 3500 High Value V6 and 3400 V6
Like the flywheel, dozens of 3100 V6 parts have been changed to allow common assembly with the 3400 and the new 3500 High-Value V6. These parts range from fasteners such as cylinder-head and manifold bolts to electrical connectors. There have also been minor casting revisions for the 3100. Such common parts reduce corporate inventory, streamline procurement practices and contribute to a common objective every automobile buyer understands: less assembly time and lower cost for a better product, which ultimately translates to more value for the customer.
Production Shifts to Tonawanda, N.Y. Engine Plant
With introduction of the 3500 High Value V6, the 3100 will be built exclusively at the Tonawanda, N.Y. engine plant (the world's largest automotive engine assembly site). The 3500 will be built exclusively at GM's engine plant in Ramos Arizpe, Mexico. Ramos will continue to manufacture some 3400 V6s for minivans and sport-utility vehicles, but the 3100 will no longer be manufactured there.
2005 Model Year
Summary of changes for the 2005 Model Year
- Long relief A500 upper and lower thrust bearing
- Exhaust manifold and gaskets
- Revised throttle body gasket material
- Modified fuel rail assembly to implement the "shrouded tip" Multec II Injectors
- 7.5 watt, post-converter oxygen sensor
Detailed Descriptions
Long Relief A500 Upper and Lower Thrust Bearing
Main bearings hold the crankshaft firmly against the bottom of the block. In contrast, thrust bearings prevent the crankshaft from moving out of position on horizontal plain. The new thrust bearings for the LG8 use a reformulated amalgam of metals providing an incremental increase in engine durability and quality.
Exhaust Manifold and Gaskets
In a move to commonize parts between engines in the 60-degree V6 family, the LG8 now utilizes the same exhaust manifolds and gaskets as the LA1 3400 and LX9 3500 engines.
New Throttle Body Gasket Material
The new material used for the throttle body gasket is improved and will incrementally enhance the long-term performance of this engine.
Multec-2 Shrouded tip Injectors and Modified Fuel Rail Assembly
Fuel quality, fuel system maintenance, environmental factors and vehicle age can all work together to clog fuel injectors. The new shrouded-tip injectors help to stave off clogging by protecting the orifice of the fuel injector with a sleeve-like cover. The orifice is recessed within the shroud, making it much more difficult for byproducts of the combustion cycle to clog the injector opening. Normally, clogged fuel injectors are only an issue on high-mileage vehicles, and this change was made to improve the owner satisfaction levels of long-term owners. The fuel rail assembly required modification to accommodate the new injectors.
Oxygen Sensors
These new sensors improve diagnostic capabilities for the on-Board Diagnostic II system (OBD II). This benefit helps improved long-term serviceability.[[Category: 3100]]
