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Charger Tech Training…the 3.5L SOHC V-6
The police Charger is available with one of two engines, the 250-hp 3.5L V-6 and the 345-hp (and now 370-hp) 5.7L HEMI® V-8. The standard Charger engine is the 250-hp V-6, which gives the Charger about the same acceleration and overall performance as the 250-hp V-8 Ford CVPI.
The Charger’s 3.5L V-6 is a single overhead cam (SOHC) engine, like the 4.6L V-8 used in the Ford CVPI. Chrysler has a separate two-day technician training course specifically for its cam-in-head (OHC) engines. This course is geared for techs already familiar with basic engine repair procedures and covers just the unique aspects of their overhead cam engines.
Law enforcement got its first glimpse of this 3.5L V-6 in late-2000 when DaimlerChrylser ran a prototype 2001 Dodge Intrepid at the Michigan State Police tests. When the 2002 Intrepid was formally tested by the MSP in late-2001, it became the first patrol sedan to reach a top speed of 135 mph since the 1996 LT-1 powered Caprice. However, the 3.5L SOHC V-6 is much more street proven than the police experience starting in 2002. The 3.5L engine made its debut in the 1993 retail Dodge Intrepid and Chrysler Concorde.
Major Engine Advancement
The single overhead cam V-6 engine was a major powertrain advancement for Chrysler. The 3.5L engine has two separate intake manifolds and throttle bodies connected with a crossover valve. This helps the low and mid-range torque, which is always an issue with any SOHC engine. The 3.5L V-6 has four valves per cylinder actuated by a single camshaft per cylinder head. (Many four-valve engines use dual overhead cams.)
The 3.5L V-6 uses a cast aluminum block, cast aluminum heads and cast aluminum lower intake manifold. Like the 5.7L V-8, the 3.5L V-6 is not free-wheeling. That means, if a timing belt or chain fails, the pistons may contact and damage the valves.
The original “EGJ” 3.5L engine was upgraded in 1999 to the “EGG” High Output engine. That year the 3.5L engine was redesigned to also work with a rear-wheel drive layout. Over the years, the output has been bumped from 214 hp to 234 hp to its current 250 hp.
The 3.5L V-6 uses a coil-on-plug (COP) ignition system. This V-6 also uses 100K-mile platinum spark plugs with a washer-type seat. Just like the Ford CVPI engine, the aluminum heads must be cool (cold) before the spark plugs are removed. The spark plug torque of 13 lb-ft is critical. Spark plug thread repair on an aluminum head seldom works.
The timing drive system consists of a single notched timing belt driven by the crankshaft. This belt drives the left and right camshaft sprockets and the water pump. The system uses a hydraulic timing belt tensioner at the lower right front corner of the engine. The timing belt should not need to be replaced during the life of the engine.
The 3.5L cylinder heads used a cross-flow intake and exhaust ports. They are interchangeable between the left and right cylinder bank simply by reversing the direction of the head during installation.
Long Ram, Short Ram
The 3.5L V-6 uses a cross flow, long runner intake manifold design to improve low-end torque. The high-output version of this engine used in police Chargers also has a short runner valve (SRV) that redirects airflow into short intake runners for better high-end horsepower. The SRV opens under wide open throttle above 5,000 rpm. The SRV solenoid actuates a mechanical linkage converting the 3.5L intake from a “long ram” air flow to “short ram.”
This is a performance trick pioneered by Chrysler in the 1950s. A PCM-controlled manifold tuning valve is located on a passageway between the two split plenums in the intake manifold. This adjusts plenum volume based on engine load and rpm. The MTV connects the plenums at low engine speed to maximize torque and splits the plenums at high rpm to maximize horsepower.
Oil and Cooler?
The 3.5L V-6 uses an auxiliary engine oil cooler integrated with the oil filter housing. This is an oil-to-coolant cooler (not an oil-to-air cooler) mounted between the oil filter and oil pan. Engine coolant flows into the oil cooler from the heater core return tube and exits into the water inlet tube. For its part, engine oil travels from the oil cooler into the oil filter, then into the main oil gallery.
The 3.5L SOHC V-6 used in the police Charger uses 10W-30 engine oil. Note that this is totally different from the 5W-20 oil required for the 5.7L HEMI V-8 in the police Charger. Use the right weight of oil for each engine! The oil change interval is 6,000 miles.
Test Your Knowledge of 3.5L V-6
Pop quiz. True or false, the 3.5L rocker arms are Y-shaped using one cam lobe to actuate two exhaust valves. True, but the intake side uses one cam lobe per valve. True or false, the left bank cam and the right bank cam on the 3.5L SOHC engine are identical. False, the left cam is longer.
Where is the water pump on a 3.5L V-6 engine? The water pump bolts directly to the inner front cover and cylinder block, behind the outer front cover. The water pump is driven by the backside of the timing belt.
Last question. Where is the coolant thermostat on the 3.5L V-6 used in the LX (Charger)? The location on the 3.5L LX engine is different from all other 3.5L engines! It is located on the inlet side of the engine and water pump. The thermostat housing is attached to the left side of the cylinder block near the front of the engine.
The no-charge, factory tech training is available at two dozen Chrysler regional training centers across the U.S. This same police-specific training will also be available in house at the police and sheriffs departments running larger fleets of Chargers. For more information, contact George Bomanski, the regional fleet service manager at firstname.lastname@example.org. They are scheduling these two-day classes about six month in advance. Since the training is definitely hands on, the class size is limited to 12 techs.
Published in Police Fleet Manager, Mar/Apr 2009
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