DESCRIPTION
The 2.4 Liter (148 cu. in.) in-line four cylinder engine is a double over head camshaft with hydraulic lifters and four valve per cylinder design. The engine is free-wheeling; meaning it has provisions for piston-to-valve clearance. However valve-to-valve interference can occur, if camshafts are rotated independently.
The cylinders are numbered from front of the engine to the rear. The firing order is 1-3-4-2.
The engine identification number is located on the rear of the cylinder block (Scheme 170)
Scheme 170
The cross flow designed, aluminum cylinder head contains dual overhead camshafts with four valves per cylinder (Scheme 171) The valves are arrange in two in-line banks. The intake valves face toward the left side of the vehicle. The exhaust valves face the right side. The cylinder head incorporates powdered metal valve guides and seats. The cylinder head is sealed to the block using a multi-layer steel head gasket and retaining bolts.
Integral oil galleries providing lubrication passages to the hydraulic lash adjusters, camshafts, and valve mechanisms.
Scheme 171
OPERATION
The cylinder head closes the combustion chamber, allowing the pistons to compress the fuel/air mixture for ignition. The valves are actuated by the lobe profiles on the camshaft to open and close at specified duration to either allow clean air in the combustion chamber or the exhaust gases out; depending on the stroke of the engine.
Both nodular iron camshafts have six bearing journal surfaces and two cam lobes per cylinder (Scheme 172) Flanges at the rear journals control camshaft end play. Provision for a cam position-sensor is located on the exhaust camshaft on the front of the cylinder head. A hydrodynamic oil seal is used for oil control at the front of the camshaft.
Scheme 172
The camshaft is driven by the crankshaft via drive sprockets and belt. The camshaft has precisely machined lobes to provide accurate valve timing and duration.
Scheme 173
- Oil camshaft journals and install camshaft WITHOUT cam follower assemblies. Install rear cam caps and tighten screws to specified torque.
- Using a suitable tool, move camshaft as far rearward as it will go.
- Zero dial indicator (Scheme 173)
- Move camshaft as far forward as it will go.
- Record reading on dial indicator. For end play specification, (Refer to «SPECIFICATIONS»(ref-215231-S27826710262006010900000) ).
- If end play is excessive, check cylinder head and camshaft for wear; replace as necessary.
Scheme 174
Scheme 175
- Remove cylinder head cover. (Refer to «REMOVAL»(ref-215231-S41247108762006010900000) )
- Remove camshaft position sensor and camshaft target magnet. (Refer to «CAMSHAFT POSITION SENSOR»(ref-176762-S32241224672005051100000) )
- Remove timing belt. (Refer to «REMOVAL»(ref-215231-S26883353292006010900000) )
- Remove camshaft sprockets and timing belt rear cover. (Refer to «REMOVAL»(ref-215231-S23335248322006010900000) )
- Bearing caps are identified for location. Remove the outside bearing caps first (Scheme 174)
- Loosen the camshaft bearing cap attaching fasteners in sequence shown (Scheme 175) one camshaft at a time. CAUTION: Camshafts are not interchangeable. The intake cam number 6 thrust bearing face spacing is wider.
- Identify the camshafts before removing from the head. The camshafts are not interchangeable.
- Remove camshafts from cylinder head. NOTE: If removing rocker arms, identify for reinstallation in the original position.
The four valves per cylinder are opened by using roller rocker arms which pivot on hydraulic lash adjusters. The valves have chrome plated valve stems. Viton rubber valve stem seals are integral with the spring seats. They have chrome plated stems to prevent scuffing. Viton rubber valve stem seals are integral with the spring seats. The valves, spring retainers, and locks, are the 3 - bead lock design
The cast iron cylinder block is a two-piece assembly, consisting of the cylinder block and bedplate (Scheme 176) The bedplate incorporates the main bearing caps and bolts to the cylinder block. This design offers a much stronger lower end and increased cylinder block rigidity. The rear oil seal retainer is integral with the block. The bedplate and block are serviced as an assembly.
Scheme 176
The crankshaft is made of nodular cast iron and includes five main bearing journals and four connecting rod journals (Scheme 177) The number three journal is the location for the thrust bearing. The mains and connecting rod journals have undercut fillet radiuses that are rolled for added strength. To optimize bearing loading, eight counterweights are used.
Scheme 177
The crankshaft transfers force generated by combustion within the cylinder to the flywheel or flexplate.
Scheme 178
- Using Dial Indicator C-3339 and Mounting Post L-4438, attach to front of engine, locating probe perpendicular on nose of crankshaft (Scheme 178)
- Move crankshaft all the way to the rear of its travel.
- Zero the dial indicator.
- Move crankshaft all the way to the front and read the dial indicator. Refer to «SPECIFICATIONS»(ref-215231-S27826710262006010900000).
The pistons are made of a cast aluminum alloy. The pistons have pressed-in pins attached to forged powdered metal connecting rods. The pistons pin is offset 1 mm (0.0394 in.) towards the thrust side of the piston. The connecting rods are a cracked cap design and are not repairable. Hex head cap screws are used to provide alignment and durability in the assembly. The pistons and connecting rods are serviced as an assembly.
The piston and connecting rod is the link between the combustion force to the crankshaft.
The engine mounting system consist of three mounts; right and a left side support the powertrain, and rear mount to control powertrain torque. The mounts are of molded rubber material.
The lubrication system is a full-flow filtration, pressure feed type. The oil pump is mounted in the front engine cover and driven by the crankshaft.
Engine oil drawn up through the pickup tube and is pressurized by the oil pump and routed through the full-flow filter to the main oil gallery running the length of the cylinder block. A diagonal hole in each bulkhead feeds oil to each main bearing. Drilled passages within the crankshaft route oil from main bearing journals to connecting rod journals. Balance shaft lubrication is provided through an oil passage from the number one main bearing cap through the balance shaft carrier support leg. This passage directly supplies oil to the front bearings and internal machined passages in the shafts that routes oil from front to the rear shaft bearing journals. A vertical hole at the number five bulkhead routes pressurized oil through a restrictor (integral to the cylinder head gasket) up past a cylinder head bolt to an oil gallery running the length of the cylinder head. The camshaft journals are partially slotted to allow a predetermined amount of pressurized oil to pass into the bearing cap cavities. Lubrication of the camshaft lobes are provided by small holes in the camshaft bearing caps that are directed towards each lobe. Oil returning to the pan from pressurized components supplies lubrication to the valve stems. Cylinder bores and wrist pins are splash lubricated from directed slots on the connecting rod thrust collars.
The engine oil filter is a high quality full-flow, disposable type. Replace the oil filter with a Mopar(R) or the equivalent.
Scheme 179
- Raise vehicle on hoist.
- Position an oil collecting container under oil filter location. CAUTION: When servicing the oil filter avoid deforming the filter can by installing the remove/install tool band strap against the can to base lock seam. The lock seam joining the can to the base is reinforced by the base plate.
- Using a suitable filter wrench, turn oil filter (Scheme 179) counterclockwise to remove.
The 3-wire electrical/mechanical engine oil pressure sensor (sending unit) is located in an engine oil pressure gallery.
The oil pressure sensor uses three circuits. They are
- A5 volt power supply from the Powertrain Control Module (PCM)
- A sensor ground through the PCM's sensor return
- A signal to the PCM relating to engine oil pressure
The oil pressure sensor has a 3 wire electrical function very much like the Manifold Absolute Pressure (MAP) sensor. Meaning different pressures relate to different output voltages
A 5 volt supply is sent to the sensor from the PCM to power up the sensor. The sensor returns a voltage signal back to the PCM relating to engine oil pressure. This signal is then transferred (bussed) to the instrument panel on either a CCD or PCI bus circuit (depending on vehicle line) to operate the oil pressure gauge and the check gauges lamp. Ground for the sensor is provided by the PCM through a low-noise sensor return.
Scheme 180
Scheme 181
Scheme 182
- Disconnect negative cable from battery.
- Remove timing belt. (Refer to «REMOVAL»(ref-215231-S26883353292006010900000) )
- Remove timing belt rear cover. (Refer to «REMOVAL»(ref-215231-S23335248322006010900000) )
- Remove oil pan. (Refer to «REMOVAL»(ref-215231-S19169106512006010900000) )
- Remove crankshaft sprocket using Special Tools 6793 and C-4685-C2 (Scheme 180)
- Remove crankshaft key (Scheme 181)
- Remove oil pick-up tube.
- Remove oil pump (Scheme 182) and front crankshaft seal.
Scheme 183
Scheme 184
- To remove the relief valve, proceed as follows: Remove the threaded plug and gasket from the oil pump (Scheme 183) Remove spring and relief valve (Scheme 183)
- Remove oil pump cover fasteners, and lift off cover (Scheme 184)
- Remove pump rotors (Scheme 184)
- Wash all parts in a suitable solvent and inspect carefully for damage or wear.
The intake manifold is a two piece aluminum casting (Scheme 185) that attaches to the cylinder head with fasteners. The manifold is a long branch design to enhance low and mid-range torque
Scheme 185
The intake manifold delivers air to the combustion chambers. This air allows the fuel delivered by the fuel injectors to ignite when the spark plug fire.
The exhaust manifold is made of Hi-Silicone Moly nodular cast iron for strength and high temperatures. The manifold attaches to the cylinder head.
The exhaust manifold collects the exhaust gasses exiting the combustion chambers. Then it channels the exhaust gasses to the exhaust pipe attached to the manifold.
Scheme 186
- Raise vehicle and disconnect exhaust pipe from the exhaust manifold.
- Lower the vehicle.
- Disconnect upstream oxygen sensor connector at the rear of exhaust manifold.
- Remove the air cleaner bracket (Scheme 186)
- Remove the heat shield.
- Remove the bolts attaching the manifold to the cylinder head.
- Remove exhaust manifold.
- Inspect the manifold. (Refer to «INSPECTION»(ref-215231-S07984211722006010900000) )
The 2.4L engine is equipped with two nodular cast iron balance shafts installed in a cast aluminum carrier attached to the lower cylinder block (Scheme 187)
Scheme 187
The balance shafts are driven by the crankshaft via a roller chain and sprockets. The balance shafts are connected by helical gears. The dual counter rotating shafts decrease second order vertical shaking forces caused by component movement.
Scheme 188
Scheme 189
Scheme 190
- Drain engine oil.
- Remove the oil pan. (Refer to «REMOVAL»(ref-215231-S19169106512006010900000) )
- Remove chain cover, guide and tensioner (Scheme 188) Also see Carrier Assembly Removal for service procedures requiring only temporary relocation of assembly.
- Remove gear cover retaining stud (double ended to also retain chain guide). Remove cover and balance shaft gears (Scheme 188)
- Remove balance shaft gear, chain sprocket retaining screws, and crankshaft chain sprocket. Remove chain and sprocket assembly (Scheme 189) Using two wide pry bars, work the sprocket back and forth until it is off the shaft.
- Remove carrier gear cover and balance shafts (Scheme 190)
- Remove four carrier to crankcase attaching bolts to separate carrier from engine bedplate.
The 2.4L engine is equipped with two nodular cast iron balance shafts installed in a cast aluminum carrier attached to the lower cylinder block see scheme 139
The balance shafts are driven by the crankshaft via a roller chain and sprockets. The balance shafts are connected by helical gears. The dual counter rotating shafts decrease second order vertical shaking forces caused by component movement.