Subaru XT 1988 Service Manual page 263

ENGINE LUBRICATION SYSTEM 2-4
Oil Pump
The oil pump is a small pump which sucks lubricant from the
oil pan, and pressurizes it to send it to each section subjected
to friction.
The trochoid pump consists of a pump casing with one lube oil
inlet and one outlet, and an inner and outer rotor.
Inner rotor
Suction stroke
drive side
Transfer stroke
Fig.
5
Oil Pressure Switch
(Oil Pressure Indicator Light Equipped
Model Only)
The oil pressure switch is attached to the oil pump case. It
monitors the oil pressure and turns on or off the oil pressure
indicator light in the combination meter.
The oil pressure switch consists of a diaphragm, which is
operated by oil pressure, a set of contacts, which are opened
or closed by diaphragm movement, and a spring, which deter·
mines when the contacts open depending on the oil pressure.
It is enclosed by a housing similar in design to a hexagonal nut
molded with phenol resin and a terminal.
Fig. 6
CD®®@@
1 Contacts
2 Diaphragm
3 Spring
4 Molded portion
5 Terminal
A6'()11
5
The inner rotor has four projections and the outer rotor has
five depressions. As the inner rotor rotates inside the outer
rotor, the clearance between the two rotors constantly varies.
The oil is pumped in accordance with this clearance change.
The trochoid pump is small and features a simple construction
which experiences fewer problems.
Del ivery stroke
Delivery stroke
Oil Pressure Gauge
Construction
GAUGE SECTION
The gauge section consists of a bimetal, pointer and scale
plate. The bimetal is wound with heat wire. The pointer moves
in response to bending of the bimetal.
Terminal
Fig. 7 Construction of the gauge section
SENDER SECTION
Temperature
compensating
bimetal
L2-1564
This section consists of a diaphragm, point arm, contact points
and a heat-wire-wound bimetal. The diaphragm is displaced by
oil pressure and the point arm conveys diaphragm displace-
ment to the contacts.
It is completely enclosed by a cover equipped with a positive
terminal.