3400 Yearly changes
From GM Wiki
3400 Yearly Changes and Updates
Overview
The 3400 V6 was developed for the 1996 Chevy Venture, Olds Silhouette and Pontiac Montana. The engine block is similar to the 60-degree 3.1L V6 LG8, but requires a unique casting to increase the cylinder bore by 3mm, in turn increasing overall displacement 214 cc. The 3.4L was first used in a passenger car in the 1999 Pontiac Grand Am., and its application has expanded steadily since.
Volume increased substantially in 2002, when the 3400-powered Buick Rendezvous was introduced. The engine also powered new all-wheel-drive versions of the Venture, Silhouette and Montana, and with new applications came several enhancements.
The success of the 3.4L proves that refined overhead valve technology, continually improved, meets customer needs for good specific output, a broad torque band, economy and durability at reasonable cost to both the corporation and the customer.
2001 Model Year
Summary of Changes
- 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
- New Starter Motor
- Sleeveless Coolant Sensor
- On Road Vapor Recovery (ORVR) System for Montana and Aztek
- Specific Oil Pan for Montana and Aztek
- Revised Powertrain Control Module (PCM) for Aztek
Detailed Descritptions
Better Catalysts
Improved technology increases the catalytic converter's efficiency, allowing National Low Emission Vehicle (NLEV) certification with considerably less catalyst volume and lower cost. Improved production methods allow a thin-wall catalyst substrate and new catalytic coating application. These techniques mean improved performance with less platinum, palladium and other precious metals in the catalyst. Converter volume has been reduced from 163 ci to 116 ci in the Grand Am, and from 163 ci to 134 ci in the Montana. The 134 ci converter for the 2001 Aztek is supplied by Zeuna Starker.
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 LA1s. 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 forward oxygen sensor with a 6.6-watt heating element, the air gap downpipe speeds emissions light-off time by as much as five seconds. As a result, in passenger car applications the LA1 needs no Air Injection Reaction (AIR) for National Low Emission Vehicle (NLEV) certification. Eliminating the AIR system eliminates assembly parts and reduces cost.
LA1s for the Montana and Aztek carry over with AIR, and are Ultra Low Emission Vehicle (ULEV) certified in California and select Northeast states.
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.
Lifer 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.
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.
Coolant Sensors
The coolant temperature sensor uses a plastic insulator to protect electrical leads inside the brass housing, rather than a rubber sleeve. The new sensor reduces the possibility of assembly rejection or shorting in operation. The low-coolant-level sensor is deleted on LA1s for Montana.
Full ORVR Applicaiton
The Montana and Aztek are equipped with an on-Road Vapor Recovery System that keeps gasoline vapor from escaping into the atmosphere. The evaporative canisters on the Venture, Silhouette and Montana have a capacity of 2.1 or 3.1 liters, depending on fuel tank capacity. The canister on the Aztek has a capacity of 2.1 liters.
AWD Modifications
LA1s for Montana and Aztek are fitted with a model-specific oil pan. The pan has special bosses to accommodate a brace for the power drive unit on vehicles equipped with all-wheel drive. Further, the Aztek has a revised transmission bracket with an additional "pencil brace" to secure the power drive unit.
Revized PCM for Aztek
The Powertrain Control Module on LA1s for the Pontiac Aztek adds additional software to monitor sensors and manage the optional all-wheel-drive system.
Continuing Features
Revisions for model year 2000 enhanced performance and durability in the 3400 V6. The cylinder heads and oil pan were fitted with new, leak-resistant gaskets. 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 3400 V6 was developed for the 1997 Montana. It shares its engine block with the 60-degree LG8 V6, increasing displacement 200 cc by increasing cylinder bore three millimeters. The LA1 was first used in a passenger car in the 1999 Grand Am.
"With the 3400, we are definitely serving up a good engine for the cost of production. It works because it satisfies customer demands with low cost of ownership. Platform teams want it for exactly that reason." --Mike Parise, Model Year Manager, 60-degree V6 engines.
Leadership
The LA1 proves that refined overhead valve technology, continually improved, meets customer needs for good specific output, a broad torque band, economy and durability at reasonable cost to both the corporation and the customer.
2003 Model Year
Summary of changes for 2003 Model Year
- Revised Crankshaft Bearing and Timing Ring
- Revised Cylinder Heads
- Revised Pushrods
- Revised Camshaft Journal
- Water Pump
- Air Injection Reaction (AIR) Eliminated
- Iridium Spark Plugs
- Maximum Oil Change Interval Extended
- Improved Starter Solenoid
Detailed Descriptions
Revised Crankshaft Bearing and Timing Ring
The thrust bearing on the 3.4L V6 (LA1) has been modified to optimize piston and bore oiling. The thrust bearing is fitted to the 3400's 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 even longer engine life.
3400s built for Chevy Venture, Pontiac Montana and Oldsmobile Silhouette also have a new crankshaft reluctor or timing ring. In other 3400s the timing ring is machined into the middle of the crankshaft. Those built at Ramos, Arizpe, Mexico plant have a new assembled ring. This two-piece, fine-blank ring is heat-shrunk on the crankshaft and encoded with a 24X tooth pattern. This timing ring provides the basis for future 3400 developments.
Revised Cylinder Heads
The 3.4L cylinder head castings are tapped with 8-millimeter holes for the rocker arm bolts, reducing the tap size from 10 millimeter, and the rocker arms are secured with 8-millimeter bolts. This change commonizes machining and increases assembly efficiency.
Revised Pushrods
Pushrods in the 3.4L are no longer heat-treated. The pushrod guides are now made of low friction nylon, rather than steel, and no longer need heat-treating to limit wear.
Revised Camshaft Journal
The 3.4L front camshaft journal has been revised with a new timing pattern. This journal is now machined with a 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 LA1 development.
Water Pump
The 3.4L water pump has a more efficient impellor 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.
AIR Injection Reaction (AIR) Elimindated
The AIR system has been removed for most applications. AIR was used to lower exhaust emissions by injecting warm, fresh air into the combustion process to create an exothermic reaction. The reaction warmed the catalytic converter more quickly, speeding catalyst light-off and reducing emissions during cold starts--a critical phase in certification tests. AIR has become redundant because of efficiency improvements in catalytic converters, spark plugs, oxygen sensors and engine management calibration. The 3400 meets all 2003 federal and California emission standards without AIR.
For 2003, AIR is removed from 3400s for Chevrolet Venture, Pontiac Montana and Aztek, Oldmobile Silhouette and Buick Rendezvous (the system had been removed from passenger car applications prior to 2003). AIR continues on engines exported to Europe, where regulation requires lower oxides of nitrogen (NoX) emissions. These engines are equipped with a new air pump.
Iridium Spark Plugs
The 3.4L benefits from the latest spark plug technology. The new plug has an iridium core in the conductor and the same internal resistance. Iridium helps maintain spark density over the life of the plug. The tip is still coated with platinum, and the spark 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 3.4L. 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, or 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 oilÂ’s anticipated life under some generalized operating cycle. In the 3.4L, 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, 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 and trucks equipped with the 3400 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 3.4-liter engines 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 a material called 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 Cylinder Head Gaskets
- Improved Water Pump
- Improved Sealing
- Improved Cam Bearings
- Improved Starter for Minivans and Sport-Utility Vehicles
- More Efficient Catalytic Converter
- Air Injection Reaction (AIR) Eliminated on Minivans for European Export
- Improved Bearings
- Improved Flywheel
- Changes for Common Assembly with 3500 High Value V-6
- Production shifts to Tonawanda, N.Y. Engine Plant
Detailed Descriptions
GRAPHITE CYLINDER HEAD GASKETS
The 3400 V-6 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 3400 V-6’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 3400 V-6 have been improved, including the head gaskets and water pump seal (above) and 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 Starter for Minivans and Sport-Utility Vehicles
Starters for 3400s in the Buick Rendezvous, Chevrolet Venture, Pontiac Aztek and Montana and Oldsmobile Silhouette feature a new solenoid design. With all-wheel-drive, the solenoid in these vehicles can be exposed to the “splash path”, or the area where water is thrown up by the drive wheels. The solenoid now has a vent, which allows any collected moisture to dissipate quickly, ensuring peak starter performance during cold cranking.
More Efficient Catalytic Converter
The catalytic converter for the 3400 V-6 has been improved to perform more efficiently with less precious metal in the catalyst’s substrate. A combination of metals such as platinum, palladium and rhodium in the substrate create the chemical reaction the turns exhaust emissions into carbon dioxide and water vapor. For 2004, this combination has been reformulated using more of the common varieties of these metals and less of the rarest types. The metal reformulation means equal or improved catalytic converter performance with a reduction in the overall quantity of precious metals and a significant reduction in cost.
Air Injection Reaction (AIR) Eliminated
The AIR system has been removed from 3400 V-6s in GM minivans built for European export. These 3400s were the last equipped with AIR.
AIR was used to lower exhaust emissions by injecting warm, fresh air into the combustion process to create an exothermic reaction. The reaction warmed the catalytic converter more quickly, speeding catalyst light off and reducing emissions during cold starts—a critical phase in certification tests. AIR has become redundant thanks to efficiency improvements in catalytic converters, spark plugs, oxygen sensors and engine management calibration, and the 3400 meets all EEU emission mandates without it. Eliminating AIR reduces cost and mass and eliminates a potential source of warranty claims.
Improved Cam Bearings
The 3400 V-6 camshaft bearing will be manufactured with Al-Tin, an alloy with more aluminum and tin content than conventional bearing material. The new bearings are lighter and more durable, and designed to reduce both noise and friction, thereby improving overall engine efficiency.
Improved Flywheel
The 3400’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 3100 V-6 LG8 and the new 3500 High Value V-6 LX9.
Changes for Common Assembly with 3500 High Value V6
Like the flywheel, dozens of 3400 V-6 parts have been changed to allow common assembly with the new 3500 High-Value V-6. These parts range from fasteners such as cylinder-head and manifold bolts to electrical connectors. There have also been minor casting revisions for the 3400. 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 V-6, production of the 3400 will be concentrated at the Tonawanda, N.Y. engine plant (the world’s largest automotive engine assembly site). The 3500 will be built exclusively at Ramos Arizpe, Mexico. That plant will continue to manufacture some 3400s for minivans and sport-utility vehicles, but 3400 production will be concentrated at Tonawanda.
