Timing Belt System
A single belt is used to drive both camshafts and the water pump. This provides
more precise valve timing. The cam belt width is 30mm (1.18 inches) to increase
cam belt life. The belt is constructed of wear resistant double canvas and heat
resistant rubber materials with a wire core. A round tooth profile is used for quieter
operation. The belt has an automatic cam belt tensioner which allows for thermal
expansion and contraction. The cam belt path is from the crankshaft sprocket to the
tensioner, to the left camshaft sprocket, to the water pump pulley, to the lower left
idler to the lower right idler, to the right camshaft sprocket, to the upper right idler
and back to the crankshaft sprocket.
The cam belt covers and dust seals are resin molded and protect the timing belt
from dust and water. There are additional dust seals on the left and right inner cov-
ers. These seals increase protection of the cam belt from dust and water and also
improve cam belt noise isolation.
Cooling System
The water pump pulley is driven by the back side of the timing belt. The pump
is mounted to the lower front of the engine. The thermostat is located in the lower
part of the pump housing. This location provides even engine warm-up by improved
metering of the coolant temperature. The thermostat senses the temperature of the
crankcase and radiator coolant as it is mixed.
Because the thermostat housing is located on the lower front of the engine,
all of the coolant must be drained to change the thermostat.
The heater core also serves as the by-pass system.
Oil Pump
The trichoid gear type oil pump is driven directly by the crankshaft. The pump
is bolted to the front of the engine for serviceability. The relief valve located in the
pump regulates oil pressure to 71 psi (5 kg-cm
2
). The filter by-pass valve is located
in the oil filter.
The oil pump has a reservoir which maintains oil for rotor lubrication. This is
especially helpful when the engine has not been operated for extended periods of
time. The reservoir also provides emergency oiling for the pump if there is a tem-
porary loss of oil supply.
2.2L Engine Servicing & Diagnostics
In Vehicle Servicing
The following services may be completed without removal of the engine from
the vehicle.
• Removal/replacement of cam belt
• Water pump removal/replacement
• Oil pump servicing
• Intake manifold
• Rocker covers
• Rocker arm assemblies
• Cylinder head removal
• Camshafts
• Turbocharger
End Wrench
The
8
Subaru 2.2 Liter Engine
Timing Belt
Cam Belt Tensioner
Water Pump
Oil Pump
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