1990 MITSUBISHI ECLIPSE Service Manual

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ENGINE- General information9-5
6EN0362Lb.. - -. __
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9-6ENGINE -General Information
6EN0363.-- -- -.. _-44

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ENGINE- Base Engine9-7I
BASE ENGINE
Valve seat
Squish area
Spark plug hole
Exhaust portintake port
Piston O.D.
6EN0076Camshaft lubricatingValve guide
6ENO246Camshaft lubricating
oil passage
6ENO247
(1) The combustion chamber is of the pentroof(2) The spark plugs are located at the center of the
type. The two intake and two exhaust ports arecombustion chambers.
in a crossflow arrangement. There is a
squish(3) The camshaft bearings are placed at six loca-area provided in the combustion chamber,tions on the intake side, and six on the exhaust
which promotes turbulence, further mixing ofside (see next page illustration). The thrust load
the air-fuel mixture, and more efficient
combus-of each camshaft is transmitted to the No. 1
tion.
bearing.
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9-8ENGINE - Base Engine
0
Ri
Bearing cap No.
No. 6R: Exhaust side
cyL: intake stdeNo. 5\-
CLNo.4 bd
P
j
CamshaftQsproc:kets -
sideintake sideno. 16EN0077ROCKER COVER
Rocker cover
From airintake
hose
erection that the spark
plug cable is installed.
6EN0378Breather plate
Rocker cover
To intakemanifoldPositive crankcase
ventilation valve
Viewed from bottom
of rocker cover
l Blow-by gas
C$ Fresh air6EN0384Installed inside the rocker cover is the breather plate. Theblowby gas passes through the space between the breather
plate and rocker cover and is drawn through the positive-
crankcase-ventilation valve to the intake manifold. As a result,
-fresh air is drawn to the engine cylinders.

CYLINDER BLOCKENGINE
- Base Engine9-9
Engine oil tocylinder
headCoolant inlet
ASilent
front
Engine oil main gallery
Silent shaft bearing,
rear
\shaft bearing,
A taw
Silenishaft bearing.
rearengine only)
6EN0246
(1) There is an oil jet provided for each cylinder just under the
main gallery of the cylinder block. When the pressure of oil
from the main gallery exceeds 200
kPa (2 kg/cm’, 28 psi),
the oil pushes open the check valve, spurting over the
inside of the piston, thus cooling it. (Turbo engines only)
(2) The water jacket is the Siamese type.

9-10PISTONENGINE- Base Engine
For non-turbo engineldentificatlonForturbo engine
Pin;nterline y FPiston ceyerline
6EN01246EN0125Steel strut6EN0249
Ij(1) The piston is the autothermic type with steel
struts cast into it..(2) The depth of the trough in pistonhead varies for
the non-turbo and turbo engines.
Piston
pinConnecting
rod?\i
~Piston
6EN0250
No. 1 piston ringPISTON RINGS
No.3
For turbo engine
(1) The No. 1 piston ring IS of the barrel type.
(2) The No. 2 piston ring is of the taper type. The surface in
contact with the cylinder wall is coated with hard chrome
plating.-
(3) The oil ring is of the three piece type, consisting of two sLrails and an expander.
.,YM,,fiFNflR7
,
(3) The piston pin is of the semi-floating type, press-fitted to
the connecting rod and rotates freely in the piston.

ENGINE- Base Engine9-11 7Oil jet
Front mark
6ENOO6lCONNECTING ROD
(1) The same connecting rod is used as that used in the 4663SOHC engine.
(2) The oil jet provided in the shoulder of the connecting rod is
used to lubricate the cylinder wall.
(3) The big-end bearing is the kelmet metal with metal backing.
CRANKSHAFT(1) The crankshaft is supported by the five main bearings.
(2) The oil passages drilled to the crankpins permit the flow of
lubricating oil from the main bearing to the connecting rod
bearing.(3) The crankshaft has been subjected to special surface
treatment. Therefore, do not grind it for reuse.
(4) The main bearing is an aluminum alloy with a backing of
another metal. The center bearing is provided with flanges
to receive the thrust load of the crankshaft.
Oil passage
6EN0089
16ENOOQO
Oil passage
INo. 51MAIN BEARING CAPSThe No. 1 and No. 2 main bearing caps are joined, as are the
No. 4 and No. 5 main bearing caps, by means of a beam to
minimize vibration of the bearing saddles and to enhance
rigidity of the crankshaft support.
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