Audi V8 Assembly instructions

Service.
For internal use only
All rights reserved. Subject to
technical modifications.
AUDI AG
Abteilung I/VK-5
D-85045 Ingolstadt
Fax [phone]
940.2810.36.20
Technical status 02/99
Printed in Germany
The V8-5V Engine
Construction Features and Functions
Self-Study Programme 217
217
217

2
SSP217_048
AUDI has been producing advanced 8-cylinder
engines since 1988. Their capacity has increased
from 3.6 l to 4.2 l.
The V8 engine in combination with Aluminium
Space Frame technology was the technical basis
forAudi's breakthrough into the luxury class.
Steps to enhance the value of the Audi A8 have
included the redesign of the V8 engine.
The new V8-5V engines are now also available for
the Audi A6 model range.

3
Engine - Motronic Subsystems
Variable intake manifold ...................................................... 27
Secondary air system ........................................................... 32
Content
Introduction
Engine - Mechanics
Crankgear .............................................................................. 6
Engine mounting .................................................................. 9
Engine lubrication ................................................................ 10
Cooling circuit ....................................................................... 16
Cylinder head
Five-valve technology ............................................. 19
Roller rocker ............................................................ 20
Camshaft adjuster .................................................. 22
Toothed-belt drive; cylinder-head seal ................. 24
Cylinder-head cover seal ........................................ 25
Exhaust manifold .................................................... 26
Technical data ....................................................................... 5
The self-study programme is not a repair manual!
The self-study programme provides you with information
concerning the engine's construction features and functions.
New! Caution!
Important!
Page
When carrying out maintenance and repair work, it is essential
to use the latest technical literature.
Engine Management
System overview ................................................................... 36
Function diagram ................................................................. 38
Quick-start functions
Camshaft position sensor ...................................... 40
Engine run-down sensor ........................................ 41
Electronic throttle function ................................................. 42
CAN bus interfaces ............................................................... 44
Additional signals / interfaces ............................................ 46
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4
New features
– Five-valve cylinder head with roller rocker
– Camshaft adjustment
– 3-stage variable intake manifold
– Engine management system, Bosch ME 7.1
– Electro-hydraulic engine mounting
Modifications
– to crankcase and crankgear
– to oil circuit
– to cooling circuit
V8-5V Engines
Introduction
SSP213_073
Major modifications were made to the
V8 engines during the course of further
development.
Emphasis was placed on the following
development objectives:
– compliance with future exhaust-emission
regulations
– reduction of fuel consumption
– increase in torque and power
– improvement of comfort and convenience
– reduction of engine weight
– increased use of shared components for
the AUDI engine series.
The following new features and modifications
have been incorporated in the V8 4-valve
engine.

5
Technical data
The specified power data is only
possible if 98 RON fuel is used.
A reduction in power output must be
expected if 95 RON fuel is used.
3.7 l V8-5V engine
4.2 l V8-5V engine
0
50
100
150
200
250
300
350
400
450
500
0
25
50
75
100
125
150
175
200
225
250
0 1000 2000 3000 4000 5000 6000 7000
0
50
100
150
200
250
300
350
400
0 1000 2000 3000 4000 5000 6000 7000
0
25
50
75
100
125
150
175
200
SSP217_004
SSP217_005
Torque (Nm)
Speed (rpm)
Power output (kW)
Torque (Nm)
Speed (rpm)
Power output (kW)
3.7 l 4.2 l
Engine code AQG AQF (A8)
ARS (A6)
Design V8 engine with 90
o
V angle
Capacity 3697 cm
3
4172 cm
3
Power output 191 kW
260 hp
at
6000 rpm
228/220 kW
310/300 hp
at
6000 rpm
Specif. output 51.6 kW/l
70.3 hp/l 54.6 kW/l 74.3 hp/l
Torque 350 Nm at
3200 rpm 410 Nm at 3000 rpm
Specif.
torque 94.7 Nm/l 98.3 Nm/l
Bore 84.5 mm 84.5 mm
Stroke 82.4 mm 93.0 mm
Compression
ratio 11:1 11:1
Weight 198 kg 200 kg
Engine
management Motronic ME 7.1
Fuel 98/95 RON
Firing
sequence 1 - 5 - 4 - 8 - 6 - 3 - 7 - 2
Exhaust-emis-
sion standard EU 3

6
Engine - Mechanics
Crankgear
The crankcase has been adapted to the
modifications made to the oil supply system
and cooling circuit.
Cracked-steel conrods have been used forthe
3.7 l engine since 1995 and are now also
being used for the 4.2 l engine.
The conrods are shared components used in
both the 2.4 l and 2.8 l engine.
SSP217_054
SSP217_006

7
Owing to the design of the valve recesses, the
pistons are specificallyintended for use in the
appropriate cylinder bank only.
SSP217_055
SSP217_002

8
Engine - Mechanics
The locking mandrel (V.A.G 3242) used for the
V6 engines is also used for locking the
crankshaft. It is applied to the crank web of
the 4th cylinder and is used for basic engine
adjustment and also as a counterhold for
loosening and tightening the central bolt of
the crankshaft.
SSP217_009
The 5th cylinder must be set to
ignition TDC.
SSP217_007
Wide, milled ventilation recesses above the
thrust bearings reduce pumping losses.
Bolts are also inserted at the side of the two
front crankshaft bearing caps to improve
running smoothness
(see SSP 198, page 6).

9
The central bolt does not have to be
unscrewed for the vibration damper to be
removed.
The marking indicates the ignition TDC of the
5th cylinder.
SSP217_050
Central bolt
Marking
Engine mounting
To enhance driving comfort, hydraulic engine
mounts with electrical activation are used for
the 8-cylinder engines.
They function in the way as described in
SSP 183/16.
The mounts are activated by the engine
control unit according to engine speed and
vehicle speed.
Electrical connection
SSP217_039

10
Engine - Mechanics
SSP217_010
A duocentric oil pump driven by the cranks-
haft via a chain replaces the previously used
external gear oil pump.
The duocentric oil pump extends deep into
the oil sump. The low suction height means
that the oil pressure can build up quickly,
especially with cold-starts.
The oil-pressure control valve is located in the
oil pump housing. The “diverted“ oil is led off
to the intake side of the oil pump. This helps
optimise the level of efficiency.
In the intake spindle shafts, there are 5 oil
bores per triple roller rocker. Three oil bores
each supply one hydraulic tappet. Two oil
bores supply the oil-spray bores integrated in
the roller rocker to lubricate the rollers. The
oil-spray bores are only opened when the
roller rockers are actuated. This results in a
reduction of the amount of oil required in the
cylinder head.
Oil-level sensor
Triple roller rocker
The roller rockers are described on
pages 20 and 21.
Engine lubrication

11
BA
A
B
B
P
A
A
SSP217_011
Throttle
Cylinder bank 1
Oil retention valves
Spray jet valve
Bypass valves
Oil filter module
Oil sump
Oil pressure control
valve
Camshaft
Cylinder bank 2
Oil flow (pressurised)
Oil flow (non-pressurised)
Throttle
Duocentric oil pump
Filter element Oil cooler
Slight modifications have been made to the
oil circuit in the cylinder heads.
The oil circuit forcylinder bank 2 shown in the
illustration is the oil circuit that has been
used since the introduction of the new model.
Cylinder bank 1 shows the modified oil
circuit.

12
Engine - Mechanics
The oil filter module contains the oil filter
and oil cooler. It is also used to hold the
alternator.
SSP217_013
Oil cooler bypass valve
Alternator mount (part
of oil module)
Coolant supply
Coolant
return
Oil supply
Oil return
Oil filter module (A8)
Oil pressure switch
Drain plug
Filter bypass
valve
As was previously the case, the oil cooler is
designed as a coolant-to-oil heat exchanger.
The “housing-less“ oil cooler is bolted to the
oil filtermodule using an O-ring seal to form a
single unit.

13
SSP217_014
Oil cooler
O-ring seal
Sealing surface
(Oil cooler)
Coolant supply
(from engine)
Oil duct
Coolant
return Oil cooler bypass valve
Oil return
(to engine)
Oil supply
(from engine)
Oil cooler
return
Oil cooler
supply
Plastic con-
nection
SSP217_003
Oil filter cartridge
Alternator
holder
For space reasons, the A6 oil filter module is
fitted with an oil filter cartridge.
Oil filter module (A8)
Oil filter module (A6)
Engine oil
Coolant Coolant supply

14
Engine - Mechanics
The pitch of the internal gear and the
external runner has no functional
significance and is determined by
production engineering factors.
To ensure that the assembly
functions correctly, the narrow gears
must not run together on the same
plane.
SSP217_012
External runner
Internal gear
Oil pressure control valve
Duocentric oil pump
Oil level sensor
The oil level sensor functions as an informa-
tion sender which allows the flexible service
interval to be calculated and the oil level to be
displayed in the dash panel insert.
Further information can be found in SSP 207
(from page 84 onwards) and SSP 213 (from
page 55 onwards).
SSP217_063
Oil level sensor

15
Notes

16
Engine - Mechanics
The flow direction of the coolant has been
changed in the new V8 5-valve engines.
As with the V6 engines, the coolant leaving
the cylinder heads merges in the rear coolant
pipe from where it is then led off to the
cooler.
SSP217_015
Cooling circuit
(Example: A8)
Return from oil
cooler
Heat exchanger / valve
unit
Coolant temperature
sender G2 and G62
Radiator fan thermo
switch F18/F54
Coolant pipe
(return for heater, oil
cooler and expansion
tank) Breather pipe
New coolant pipe to
cylinder head
(small cooling circuit)

17
Oil cooler return
The new coolant pipe alters the coolant flow
in the „small“ cooling circuit.
SSP217_016
Coolant pipe
(return for heater, oil cooler
and expansion tank)
New coolant pipe to
cylinder head
(small cooling circuit)
To expansion tank (A8)
Coolant return
Heat exchanger (A6)
Breather pipe
(to expansion tank)
Coolant supply
for heat exchanger
to vehicle radiator
Coolant return
Heat exchanger (A8)
to expansion tank (A6)
Coolant temperature
sender G2 and G62
Coolant pipe (rear)

18
Previous design:
The coolant thermostat is connected to the
“small coolant circuit“ via two holes in the
cylinder crankcase (see Fig. 217_017).
The holes are directly connected to the
cylinder-head water jacket (1st cylinder) and
the waterjacket of the cylinder crankcase.The
heated coolant flows from the 1st cylinder to
the coolant thermostat.
SSP217_018
Engine - Mechanics
New design - modified components:
– Cylinder head in bank 1 modified
– Additional coolant pipe
– Rear coolant pipe modified
The connection in the cylinder head to the
water jacket (cylinder crankcase) has been
split (see Fig. 217_019).
The coolant from the rear coolant pipe is
forked by the new coolant pipe (mixture from
all cylinders) and then passes through the
cylinder head to the two holes which lead off
to the coolant thermostat.
This ensures uniform temperature control.
The function of the cylinder head is to
connect the coolant pipe to the two holes
leading off to the coolant thermostat.
SSP217_019
SSP217_017
New coolant pipe New design
From radiator
To coolant pump
Coolant thermostat
Coolant pipe
(return for heater, oil cooler
and expansion tank)

19
The rockers are made of die-cast aluminium
in order to keep inertia forces as low as
possible. As a result, the valvegear is able to
function reliably at engine speeds of up to
7200 rpm.
The use of roller rockers has not only meant a
considerable reduction in frictional losses in
the valvegear, but has also halved the oil
delivery rate in the cylinder heads. This also
has a positive effect on the degree of
efficiency.
Five-valve technology is now also being used
in the V8 engines.
Roller rockers are being used forthe first time
in the enhanced five-valve cylinder head.
This considerably reduces frictional losses in
the valvegear which, in turn, significantly
improves efficiency.
SSP217_020
Cylinder head
Five-valve technology

20
SSP217_023
Engine - Mechanics
Roller rocker
Exhaust valve
Every valve has a hydraulic valve lifter which
is integrated in the rocker. The rockers are
supported by a spindle shaft which is also
used to supply oil to the bearings and the
hydraulic valve lifters.
The two exhaust valves are actuated by a twin
roller rocker.
The single cam actuates the rocker by means
of a roller located between the rocker arms.
SSP217_022
Spindle shaft,
also used to
supply oil
Exhaust valve
20.2˚
Roller located between
rocker arms
Twin
roller rocker
Single cam
Oil spray hole
The individual hydraulic valve lifters
can be replaced without the rockers
needing to be removed.