AUDI S4 1998 B5 / 1.G Engine Manual

11
Fan control
The control unit for radiator fan V293 regulates
the output of the radiator fan and controls the
continued coolant circulation. The induced-air
fan V7 and the forced-air fan V177 are
activated simultaneously.
Forced-air fan V177 is located upstream of the
condenser, water cooler and visco fan. It
assists the visco fan.
The electronic power control
The various fan settings are executed by an
electronic power control.
The fan motors are operated periodically, the
length of the operating cycle depending on the
fan setting selected. Fan output level is
controlled via pulse-width-modulated outputs.
Should a fan fail, the radiator fan control unit
increases the speed of the fan motor still
available.
Advantages of the power control:
•
The series resistors previously used for
power control are no longer required.
•
Lower power consumption in lower fan
settings.
•
Safety functions.
The power supply is protected by a
fuse on the 8-socket relay plate. For
the correct fuse rating, please refer
to wiring diagram.
Vehicles equipped with an air
conditioner require a higher fuse
rating than vehicles without an air
conditioner.
SSP 198/50

8-socket relay plate
SSP 198/55

Control unit for radiator fan
attached to front right
vehicle side member
Fuse, terminal 30
Fuse, terminal 61

12
Electric circuit of fan control:
Engine
for vehicles with air-conditioning system:
Integrated in the pressure switch for air
conditioner F129 is the high-pressure switch
for activating a higher fan setting.
The pressure switch is mounted below the
right-hand headlight behind the bumper.
Components:
F18/F54 Radiator fan thermoswitch
F95 Thermoswitch for continued coolant
function
F129 Pressure switch for air conditioner
(only for vehicles with air conditioner)
V293 Control unit for radiator fan
V7 Radiator fan (induced-air fan)
V51 Continued coolant circulation pump
V177 Fan 2 for radiator (forced-air fan)
(only for vehicles with air conditioner)
1 Terminal 30, positive supply via fuse
on 8-socket relay plate
2 Terminal 61, D+ (alternator) via fuse on
8-way relay
3 Fan activation (only for vehicles with
air conditioner)
M_
V293 F18
F54
F129
V177V7 V51
M_
M_
SSP 198/17
*
*
F95
*
P
P
123

only for vehicles with air conditioner
Air-conditioning pressure switch F129

13
Function of fan circuit
(for vehicles with air-conditioning
system)
4 fan settings are possible:
is activated by coolant pump thermoswitch
F95.
The fan motors and continued coolant
circulation pump V51 are activated.
The fan motors run at min. output (40%).
is requested by radiator fan thermoswitch F18
or by the air-conditioning control panel.
The fan motors run at 50% output.
is activated by air-conditioning system
pressure switch F129.
The fan motors run at 85 % output.
is activated by radiator fan thermoswitch F54.
The fan motors run at full output.
Fan speeds 1, 2 and 3 are only
activated if the “engine running“
signal is picked up at terminal 61.
The electrical coolant function.....
The continued coolant function is
only activated if the “engine not
running“ signal is picked up at
terminal 61. The continued coolant
function period is limited to 10
minutes.
Fan speed 1......
Fan speed 2......
Fan speed 3......

1415
SSP 198/49

Engine
Engine lubrication
The oil circuit of the 2.7-litre V6 biturbo engine largely corresponds to that
of the 3rd V6 engine generation.
In addition, the two exhaust gas turbochargers are supplied with
pressurised oil from the main oil gallery via a distributor piece. The oil is
returned directly to the oil sump.
The oil cooler was adapted to withstand the higher thermal stresses in
comparison with a naturally aspirated engine.A new feature of the biturbo is
the “integrated oil supply“ (see
next page).
to oil filter/oil cooler
Spring-loaded slipper
(chain tensioner)
Main oil gallery
Oil retention valves
Bypass valve
Filter element
Bearing cap
Oil groove
Oil temperature
sender
Oil pressure switch
Restrictor
Oil retention
valve
distributor piece

The oil circuit
A duocentric oil pump draws in the oil
through a coarse filter. Located in the
pressure chamber of the pump is a
pressure relief valve which protects
downstream components against
pressure peaks during cold starts.
The oil is fed to the oil filter via the oil
cooler. After passing an oil retention
valve, the oil flows through the filter
element. A bypass filter is connected in
parallel with the filter element.
The oil subsequently reaches the main
oil gallery. A branch line is routed to the
oil pressure control valve (clean oil
side).
The following components are supplied
with oil from the main oil gallery:
- the four crankshaft bearings
- the two exhaust gas turbochargers
via an oil distributor line
- the three pairs of piston spray jets via
a spray jet valve
- the cylinder head of cylinder bank 1
via an oil retention valve
The cylinder head of cylinder bank 2 is
supplied through a separate bore from
crankshaft bearing 2 via an oil retention
valve also.
First of all, the camshaft adjustment
valve is supplied with oil from the inlet
drilling in the cylinder head. After the oil
has passed by a restrictor, it is
channeled via the cylinder head main
gallery to the hydraulic valve tappets
and the camshaft bearings.
Exhaust gas turbocharger
Bypass filter
Oil pressure relief valve
from oil filter/oil coolerOil pressure
control valveInduction filter
Oil pressure relief valve
from oil filter/oil cooler
to oil filter/oil cooler

16
Engine
The component parts of the oil circuit
is integrated in the primary flow. By increasing
the capacity and optimising the flow
resistance, the entire oil flow can be routed
through the oil cooler. Unlike the V6 naturally
aspirated engine, a bypass is not required.
The oil cooler ......
contains an oil retention valve, the filter
element, a bypass filter and the filter bypass
valve. The latter has the task of maintaining
engine lubrication via the bypass filter if the
filter element becomes clogged up or if the oil
has a high viscosity.
The oil filter ......
opens up the oil flow to the piston spray jets if
the oil pressure is greater than 1.8 bar.
Reason: at low oil viscosity and low engine
speeds, the oil pressure would otherwise drop
below the minimum permissible level. That
aside, piston cooling is not necessary at low
engine speeds.
The spray jets valve ......
SSP 198/57

Oil pressure control valve
Oil pressure limiting valve
Chain guard

is an internal gear pump. It is attached to the
crankcase as a separate component.
The oil pump is designed in such a way that it
projects deep down into the oil sump and is
immersed completely in the engine oil when
the oil level is correct. This prevents the oil
pump running dry.
The oil pump, in combination with the
extremely short intake path, enables oil
pressure to build up more quickly and safely,
particularly during cold starts.
The oil pump is driven by the crankshaft by
means of a single chain.
A spring-loaded flat plate produces the
necessary tension.
A new feature of the oil pump is the chain
guard made from sheet steel. It encapsulates
both the chain wheel and the chain over a large
area.
This reliably prevents oil frothing and the
problems associated with this.
The oil pump ......

17
is a pressure relief valve. It is located inside the
oil pump housing and opens when the oil
pressure rises too high (cold start). If an
excessively high oil pressure builds up,
various component parts of the oil circuit (e.g.
oil filter, oil cooler) may be damaged. Also,
there is the possibility of the inlet and exhaust
valves opening or no longer closing, due to
“bulking“ of the hydraulic tappets. The knock-
on effect of this is that the engine can no
longer be started or cuts out.
The oil pressure limiting valve ......
regulates the engine oil pressure. It is
integrated in the oil pump housing. The oil
quantity “regulated“ by the oil pressure
control valve is fed to the suction side of the
oil pump.
This helps to optimise efficiency.
The oil pressure control valve ......
prevent the oil running out of the oil filter and
the cylinder heads and back into the oil sump
while the engine is stationary.
The oil retention valves ......
The “integrated oil supply“ ...
will also be adopted for all V6 5V naturally
aspirated engines.
Each camshaft bearing is supplied via a
drilling stemming from the cylinder head main
gallery.
The oil is fed along a bolt shaft in the bearing
cap to a transverse drilling.
A lubrication groove distributes the oil
throughout the camshaft bearing. It is no
longer necessary to run a pipe to the
individual bearing caps.
Advantages:
•
Fewer components
•
Quick and even oil supply
•
No additional installation work necessary
•
Lower cost
SSP 198/58

Cylinder head main gallery
Transverse drilling

prevent “flooding“ of the cylinder heads. At
high engine speeds, an excessively large
amount of oil enters the cylinder heads and
has to be returned to the oil sump via the oil
return drillings. The restrictors reduce the oil
flow and thereby ensure that return flow takes
place.
The restrictors ......

18
Front view of engine
SSP 198/51

Engine
Camshaft adjustment
valve N208
Knock sensor G66
Intake-air temperature
sender G42
Knock sensor G61
Hall sender G163
Charge air cooler
Charge air cooler
Oil filter
Oil pressure
switch
Air-cond. compressor
Visco fan
Alternator
Power assisted steering
pump drive

19
Rear view of engine
SSP 198/52

Hall sender G40
Thermoswitch for
continued cooling
function F95
Pressure limiting
valve
Distributor piece
Coolant temperature sender F18/F54
Camshaft adjustment
valve N205
Exhaust gas
temperature sender
G235 (with evaluation
electronics)
Lambda probe
G108
Exhaust gas temperature
sender G236 (with
evaluation electronics)Lambda probe G39
SAC clutch pressure plate
Prim. catal. converterPrim. catal. converter

20
Engine
Top view of engine
SSP 198/54

Divert air valve for
turbocharger N249
Injector
Fuel pressure regulator
Solenoid valve for
activated charcoal Solenoid valve for charge
pressure control N75
Camshaft
adjustment valve
N205
Injector
Hall sender G163
Divert air valve
Charge pressure
sender G31
Throttle valve
control part
Camshaft adjustment
valve N208
Divert air valve

21
View of engine from left
SSP 198/53

Injector
Individual ignition coil
Pressure control valve
Prim. catal. converter
Exh. gas turbocharger
Pressure unit for
wastegate flap
Oil cooler
Oil filter
Charge air cooler