SPECIAL TOOLS
1023 - Puller (Originally Shipped In Kit Number(s) 8678.) 10368 - Set, Universal Protective Cap 10386 - Holder, Vibration Damper 10387 - Installer, Vibration Damper 6871 - Installer, A/C Hub (Originally Shipped In Kit Number(s) 6896.) 7700 - Tester, Cooling System (Originally Shipped In Kit Number(s) 7700-A.) 8464 - Adapter, Valve Spring (Originally Shipped In Kit Number(s) 8664, 8665, 8665CC, 8702, 9577.) 8507 - Guides, Connecting Rod (Originally Shipped In Kit Number(s) 8283, 8283CC, 8527, 8527CC, 8575, 8575CC.) 8512A - Installer, Damper (Originally Shipped In Kit Number(s) 8283, 8527, 8575, 8575CC, 8660, 8661.) 8514 - Pins, Tensioner (Originally Shipped In Kit Number(s) 8283, 8283CC, 8527, 8527CC, 8575, 8575CC, 9975.) 8534B - Fixture, Driveline Support (Originally Shipped In Kit Number(s) 8534, 8534B, 8849, 9565.) 8984-UPD - Adapter, Engine Lift (Originally Shipped In Kit Number(s) 9516, 9516-CAN, 9517, 9517-CAN, 9518, 9519.) 8984B - Fixture, Engine Lifting (Originally Shipped In Kit Number(s) 8849CC, 9329, 9515, 9516, 9518, 9519, 9540, 9541, 9577.) 9065B - Compressor, Valve Spring 9070 - Retainer, Push Rod (Originally Shipped In Kit Number(s) 8999, 8999CC, 9329, 9515, 9540, 9541, 9577.) 9071 - Remover, Seal (Originally Shipped In Kit Number(s) 8999, 8999CC, 9329, 9515, 9540, 9541, 9577.) 9072 - Installer, Seal (Originally Shipped In Kit Number(s) 8999, 8999CC, 9329, 9515, 9540, 9541, 9577, 9975, 9976.) C-119 - Cylinder Indicator C-3292A - Gauge, Pressure C-3422-D - Compressor, Valve Spring C-3685-A - Bloc-Chek Kit
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The Multiple Displacement System (MDS) selectively deactivates cylinders 1, 4, 6 and 7 during steady speed, low acceleration and shallow grade climbing conditions to increase fuel economy.
The MDS can provide a 5 to 20% fuel economy benefit when operating in four-cylinder mode. Depending on driving habits and vehicle usage. For EPA rating purposes the fuel economy is 8 to 15% higher than if the engine was operating on eight-cylinders at all times.
The MDS deactivating lifter (1) can be distinguished from the non-MDS lifter (2) by the disconnecting pin (3) on the side of the MDS lifter.
MDS is integrated into the basic engine architecture requiring these additional components
- Unique MDS camshaft
- 8 deactivating roller lifters
- 4 MDS control valve solenoids
- MDS control valve solenoid wiring harness
- Oil temperature sensor
Scheme 479
The Multiple Displacement System (MDS) provides cylinder deactivation during steady speed, low acceleration and shallow grade climbing conditions to increase fuel economy. Both four and eight cylinder configurations have even firing intervals to provide smooth operation. The MDS selectively deactivates cylinders 1, 4, 6, and 7, to improve fuel economy. All deactivated cylinders have unique hydraulic lifters that collapse when deactivated to prevent the valves from opening. Engine oil pressure is used to activate and deactivate the valves. Oil is delivered through special oil passages drilled into the cylinder block. The MDS solenoid valves control the flow. When activated, pressurized oil pushes a latching pin on each MDS lifter which becomes a lost motion link. The base of the MDS lifter follows the camshaft while the top remains stationary. The MDS lifter is held in place against the pushrod by light spring pressure but unable to move because of the much higher force of the valve spring.
Note. It is critical to use the recommended oil viscosity in engines that use MDS.
Deactivation occurs during the compression stroke of each cylinder, after air and fuel enter the cylinder. Ignition occurs, but the combustion products remain trapped in the cylinder under high pressure, because the valves no longer open. No fuel/air enters or leaves during subsequent piston strokes, this high pressure gas is repeatedly compressed and expanded like an air spring.
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- Disengage the two retaining clamps (1) and lift the cover upwards.
- Remove the air cleaner element from the inside of the air cleaner housing.