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Charger Tech Training…the 5.7L HEMI® V-8
Written by PFM Staff
About 75% of the police Chargers are ordered with the 5.7L HEMI® V-8. Chrysler divides its engines into two major groups: cam in block and cam in head. The police 5.7L V-8 is a cam in block engine, which the rest of the world calls an overhead valve engine. The police 3.5L V-6 is a cam in head engine, which the rest of the world calls an overhead cam engine. The V-6 Charger uses a single overhead cam (SOHC) engine, as does the Ford CVPI. The 5.7L OHV HEMI V-8, however, is a traditional pushrod-hydraulic lifter engine. The heads have splayed (or canted) valves, two per cylinder around a hemispherical (hemi) shaped combustion chamber.
Within each engine type, Chrysler divides its technician training service levels into three groups. First, preventative maintenance that any police shop should be able to do. Second, upper engine repairs including the intake and exhaust manifolds; rocker arms, pushrods and valves springs; and the cylinder head and valves. It will be rare for a police garage to get into the upper engine. Third, lower engine repairs including the camshaft; crankshaft; pistons and rods. It will be extremely rare for any police shop to perform a lower engine repair.
Chrysler offers a tech training course for the 5.7L V-8, (and all cam in block engines). However, this course is geared to the tech already familiar with basic upper and lower engine repairs. The course only covers the unique features of the 5.7L engine. However, all techs should be able to perform basic PM on the HEMI.
Multiple Displacement System
Since its introduction in police sedans, the 5.7L engine has used a Multiple Displacement System (MDS). Under very specific situations like low speeds, low throttle, low loads (but not idling), the Powertrain Control Module may shut off four of the eight cylinders. The MDS may also deactivate cylinders during some steady-speed, low acceleration and level grade driving conditions. It does this with a complex combination of four solenoids, an oil temperature sensor and eight unique valve lifters.
Law enforcement driving styles mean the MDS will rarely, if ever, be activated. However, the police 5.7L engine still has MDS, and the PCM still monitors the health of the MDS. This monitoring means the weights of oil used in the 5.7 V-8 is more critical than in any other police engine. TSBs 09-015-04 and 09-013-04 clearly state, “Vehicles with the Multiple Displacement System must use SAE 5W-20 oil. Failure to do so may results in improper operation of the MDS.” (This may also generate a DTC.)
So far, the MDS hardware and software has not been a significant service problem, even in police use. The proper engine oil and the proper oil change intervals are necessary to keep this good service record. The oil change interval for the 5.7L HEMI V-8 is 6,000 miles.
New for 2009
The 5.7L HEMI V-8 was introduced on the 2003 Dodge Ram...“Yeah, it’s got a HEMI.” For 2009, the 5.7L engine was upgraded to the Eagle engine. The new 5.7L engine is similar to the earlier engine but definitely different in many ways. The 2009 5.7L HEMI has new intake and exhaust manifolds; high flow ports and combustion chambers; a higher compression ratio and significantly, variable camshaft timing (VCT).
The 2009 5.7L engine uses a 10.5:1 compression ratio compared to 9.6:1 for the 2003-2008 engine. The intake manifold integrates the manifold absolute pressure (MAP) sensor, fuel rails and electronic throttle control. The new engine has larger intake valves and smaller combustion chambers. The cam used with the VCT system is totally different from earlier engines.
Variable Cam Timing
For 2009, the 5.7L engine took a big step up in complexity. The V-8 now uses variable valve timing (VVT), also called variable camshaft timing (VCT). With VCT, the camshaft itself is advanced or retarded with respect to the crankshaft. The valve timing is “advanced” at lower rpm for more torque and “retarded” at higher rpm for more horsepower. Yes, the best of both worlds.
The VCT definitely flattens the torque curve. Peak torque is increased a bit, but more important is that the torque comes on much sooner. It is this added torque (more torque under a wider rpm band) that allowed the 2009 5.7L Charger axle ratio to drop from 2.87 to 2.65 without any loss of acceleration.
A camshaft phaser changes the valve timing by changing the relationship between the camshaft and the timing chain. The phaser is actuated by engine oil pressure controlled by an oil control valve (OCV). The OCV consists of an electric solenoid and spool valve. The Powertrain Control Module actuates the OCV, which acts through a rotor, stator and sprocket to change the relative position of the cam.
Not a Viper V-10
In contrast to the Viper V-10 engine’s cam-in-cam camshaft with its variable exhaust valve, the Charger’s V-8 engine uses a single, solid camshaft. In the Viper’s 8.4L V-10 engine with a dual, cam-in-cam designs, the intake valve remained fixed while the exhaust valve was variable. In the Charger’s V-8, since a single solid cam is used, both the intake and exhaust valves and varied (advanced or retarded) by the same number of degrees and at the same time.
The 5.7L engine uses the same oil control valve as the 8.4L engine and a similar electro-hydraulic solenoid and camshaft phaser. The camshaft phaser replaces the standard cam sprocket. The OCV regulates oil flow to either side of the internal vanes in the cam phaser. This causes the phaser to rotate one way or the other and thus change the position of the cam relative to the crank. The cam phaser is bolted to the cam.
The Viper’s cam is actually two cams. The inner cam controls the intake valves and has fixed timing. The outer cam controls the exhaust valves and has variable timing. The “cam-in-cam” camshaft allows separate control of the fixed intake and variable exhaust valves. In other words, the exhaust lobes are rotated independently from the intake lobes. The camshaft consists of an inner intake shaft and an outer exhaust shaft. The exhaust lobes are pinned to the outer shaft and the intake lobes are pinned to the inner shaft.
Like the multiple displacement system, the 5.7L engine’s variable cam (valve) timing is both complex and oil-activated. Use the right weight of engine oil, 5W-20. Change it on time, 6000 miles, maximum.
The 5.7 HEMI V-8 uses two spark plugs per cylinder, 16 in all. And the 5.7L HEMI engine comes from the factory with standard-grade spark plugs. As a result, these standard plugs must be changed at the normal interval, which is just 30K miles! This is one of the very few maintenance items on the 5.7L V-8.
One fleet maintenance solution, of course, is to replace the standard plugs with premium, platinum plugs. The use of platinum plugs will extend the service interval by 100K miles. The 3.5L Charger already uses platinum plugs.
The 5.7L V-8 has aluminum heads. That means extreme care must be made when changing the spark plugs. Just like with the Ford CVPI 4.6L aluminum heads, let the heads completely cool before removing the spark plugs. Most techs let the engine cool overnight. The spark plug gap is 0.043 inches.
During installation, proper spark plug torque is extremely critical when tightening the 16 plugs into the HEMI’s aluminum head. Don’t guess. Use a torque wrench. Finger tighten the plugs until they are snug, then torque them to exactly 13 lb-ft.
Be careful. Spark plug thread repairs almost never work, and you have 16 plugs to change every 30K miles on every V-8 Charger in the fleet. Before installing the coils, apply dielectric grease to the inside of the spark plug boots. The torque for the two coil mounting bolts is 9 lb-ft.
Test Your Knowledge of the 5.7L V-8
Pop quiz. Where is the 5.7L V-8 engine coolant thermostat? It is housed in the water pump casting, on the outlet side of the water pump. On the 5.7L engine, does the coolant flow to the cast iron block before the aluminum heads? Or from the heads then to the block? Coolant goes to the block first.
On the 5.7L V-8, where is the oil pump? It is located behind the timing chain cover and driven directly by the crank. The oil pump on the 2009 and newer 5.7L engines with VCT is not interchangeable with earlier 5.7L engines. What four cylinders have both the intake and exhaust valves deactivated by the MDS? Numbers 1 and 7 on the driver’s side bank and numbers 4 and 6 on the passenger’s side bank.
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 email@example.com. 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
Rating : 9.9
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