General information about 3.7 and 4.2 liter petrol engines (Audi A8 D2)

The cars are equipped with eight-cylinder V-shaped engines (V8) with liquid cooling. The engines are located longitudinally in the engine compartment.

The engine cylinders are cast from grey cast iron as one piece with the cylinder block. The cylinder heads are made of light alloy and are bolted to the cylinder block. Steel guide bushings and valve seats are pressed into the cylinder head. An oil pan is attached to the bottom of the engine cylinder block, into which the oil needed for lubrication and cooling of the engine flows.

The engines use a cross-flow design, where the air-fuel mixture enters the engine cylinders on one side of the engine, and the exhaust gases are removed on the other side of the engine. This design significantly improves the filling of the cylinders with the air-fuel mixture and the removal of combustion products.

Each cylinder has two intake and two exhaust valves. Each section of the cylinder block has a separate cylinder head with two camshafts. One camshaft controls the intake valves, the other – the exhaust valves. The camshafts controlling the exhaust valves are driven by a single toothed belt. The camshaft controlling the intake valves is driven by the camshaft controlling the exhaust valves.

Valve clearances are adjusted automatically using hydraulic tappets, so manual adjustment is not required.

An oil pump driven by the crankshaft serves to supply oil to the engine's rubbing surfaces. Under pressure, oil is supplied through channels to the crankshaft and camshaft bearings.



The water pump is located at the front of the engine and is driven by a timing belt. Keep in mind that engine cooling system should be filled year-round with a mixture of antifreeze and low-lime water.

The fuel-air mixture is prepared and ignited in the engine cylinders by the engine management system, which does not require adjustments during operation. The ignition advance angle and idle speed are regulated by the engine management system. During maintenance, it is necessary to replace the spark plugs and the air filter element.

Warning: The radiator fan may come on after the engine has stopped and the ignition has been turned off, so be careful when working on a hot engine. To prevent the radiator fan from coming on, disconnect the electrical connector from the radiator fan motor.

Technical data

Cylinder head
Deviation from flatness of the mating surface of the cylinder head, mm	0,1
Length of toothed belt shock absorber, mm:
on a cold engine	136–139
on a hot engine	126–129
Camshaft
Maximum axial clearance of the camshaft, mm	0,15
Minimum permissible distance from the end of the valve to the upper surface of the cylinder head, mm:
aBZ engine:
intake valves	36
exhaust valves	36,3
aEW engine:
intake valves	36,4
exhaust valves	36,4
aHC engine:
intake valves	25,7
exhaust valves	36,4

Tightening torques* of main threaded connections, Nm

Torque converter to drive disc:
engine code ABZ	35
engine code AEW	85
Front right bracket to engine	45
Generator to engine:
M10	40
M8	25
Crankshaft pulley mounting bolt:
without special tool 2079	450
with special tool 2079	350
Exhaust manifold to cylinder head	25
Air Conditioning Compressor to Bracket	25
Air conditioner bracket	25
Exhaust inlet pipe to manifold	40
Front right bracket to engine	45
Lower frame to body	65 + turn 180°
Bolts for fastening the vibration damper to the crankshaft pulley	25
Timing Belt Tensioner Roller	25
Camshaft pulley mounting bolt	55
Bolt securing the sensor rotor to the rear of the cylinder head	20
Cylinder head mounting bolts:
stage 1	tighten to 40
stage 2	tighten to 60
stage 3	turn 180°
Camshaft Bearing Cap	15
Timing Belt Cover Fastening Bolts	10

* For other threaded connections, the tightening torques are as follows, Nm: M6 – 10; M8 – 20; M10 – 45; M12 – 65.