Chrysler neon 1997 Service Manual page 427

9 - 14 2.0L SOHC ENGINE
DESCRIPTION AND OPERATION (Continued)
route oil from main bearing journals to connecting
rod journals.
CAMSHAFT/HYDRAULIC LASH ADJUSTERS
A vertical hole at the number five bulkhead routes
pressurized oil through a restrictor up into the cylin-
der head. The rocker shafts route oil to the rocker
arms/hydraulic lash adjuster assemblies.
SPLASH LUBRICATION
Oil returning to the pan from pressurized compo-
nents supplies lubrication to the valve stems. Cylin-
der bores and wrist pins are splash lubricated from
directed slots on the connecting rod thrust collars.
ENGINE COMPONENTS
CYLINDER BLOCK AND BEDPLATE ASSEM-
BLY A partial open deck is used for cooling and
weight reduction with water pump molded into the
block. Nominal wall thickness is 4 mm. The bedplate
incorporates main bearing caps. Rear seal retainer is
integral with the block.
CRANKSHAFT A nodular cast iron crankshaft is
used. The engine has 5 main bearings, with number
3 flanged to control thrust. The 52 mm diameter
main and 48 mm diameter crank pin journals (all)
have undercut fillet radiuses that are deep rolled for
added strength. To optimize bearing loading 8 coun-
terweights are used. Hydrodynamic seals provide end
sealing, where the crankshaft exits the block.
Anaerobic gasket material is used for parting line
sealing. A sintered iron timing belt sprocket is
mounted on the crankshaft nose. This sprocket trans-
mits crankshaft movement, via timing belt to the
camshaft sprocket providing timed valve actuation.
PISTONS The SOHC Engine DOES NOT have
provision for a free wheeling valve train. Non free
wheeling valve train means, in the event of a broken
timing belt Pistons will contact the Valves. All
engines use pressed-in piston pins to attach forged
powdered metal connecting rods. The connecting rods
are a cracked cap design and are not repairable. Hex
head cap screw are used to provide alignment and
durability in the assembly. Pistons And Connecting
rods are serviced as an assembly.
PISTON RINGS The piston rings include a
molybdenum faced top ring for reliable compression
sealing and a taper faced intermediate ring for addi-
tional cylinder pressure control. Oil Control Ring
Package consist of 2 steel rails and a expander
spacer.
CYLINDER HEAD — SOHC It features a Single
Over Head Camshaft, four-valves per cylinder cross
flow design. The valves are arranged in two inline
banks, with the two intake per cylinder facing
toward the radiator. The exhaust valves facing
toward the dash panel. Rocker arm shafts mount
directly to the cylinder head. It incorporates powder
metal valve guides and seats. The hollow rocker arm
shafts supplies oil to the hydraulic lash adjusters,
camshaft and valve mechanisms.
CAMSHAFT — SOHC The nodular iron camshaft
has five bearing journals and 3 cam lobes per cylin-
der. Provision for cam position sensor on the cam at
the rear of cylinder head which also acts as thrust
plate. A hydrodynamic oil seal is used for oil control
at the front of the camshaft.
VALVES — SOHC Four valves per cylinder are
actuated by roller rocker arms/hydraulic lash adjust-
ers assemblies which pivot on rocker arm shafts. All
valves have 6 mm diameter chrome plated valve
stems. The valve train has 33 mm (1.299 inch) diam-
eter intake valves and 28 mm (1.10 inch) diameter
exhaust valves. Viton rubber valve stem seals are
integral with spring seats. Valve springs, spring
retainers, and locks are conventional design.
INTAKE MANIFOLD The intake manifold is a
molded plastic composition, attached to the cylinder
head with ten fasteners. This long branch design
enhances low and midrange torque.
EXHAUST MANIFOLD The exhaust manifold is
made of nodular cast iron for strength and high tem-
peratures. Exhaust gasses exit through a machined,
articulated joint connection to the exhaust pipe.
PARTS REPLACED
If any of the following parts have been changed or
replaced:
• Camshaft
• Camshaft Position Sensor
• Camshaft Position Sensor Target Magnet
• Cylinder Block
• Cylinder Head
• Water Pump
• Powertrain Control Module (PCM)
• Timing belt and tensioner.
The camshaft and crankshaft timing relearn proce-
dure must be performed. Refer to Group 25, for pro-
cedure.
DIAGNOSIS AND TESTING
CHECKING ENGINE OIL PRESSURE
(1) Remove oil pressure switch and install gauge
assembly C-3292 with adaptor.
(2) Run engine until thermostat opens.
CAUTION: If oil pressure is 0 at idle, Do Not per-
form the 3000 RPM test in the next step.
(3) Oil Pressure: Curb Idle 25 kPa (4 psi) mini-
mum 3000 RPM 170-550 kPa (25-80 psi).
(4) If oil pressure is 0 at idle. Shut off engine,
check for pressure relief valve stuck open, a clogged
PL