Audi A4

since 1994 release

Repair and operation of the car

At the left: shooters showed four high-speed locks which at removal of facing of the six-cylinder engine have to be turned on 90 ° to the left.

On the right: in the six-cylinder engine the cover of a gear belt fastens two clips (arrow). To dismantle the right cover of a gear belt, it is necessary to remove in addition a tension roller of a poliklinovy belt (a big bolt with an internal hexagon).

Too low indicators of pressure

Indicators of equally low pressure of compression yet not a reason for concern; the admissions of measurements different for different devices can be the cause of low indicators. But if at measurements on different cylinders the difference makes more than 3 bars, it is worth reflecting. It can mean the following:

• wear of pistons and piston rings;
• the piston rings which are densely sitting in flutes as a result of pollution;
• cylinders of not round form as a result of jamming of pistons;
• deposits on cores of valves or saddles of valves at the expense of products of burning and greasing;
• the burned-down valves. In most cases not tight valves and, therefore, the lowered engine capacity are the reason of insufficient pressure of compression. Only repair of a head of the block of cylinders can help.

Search of malfunctions

For localization of defect with too low pressure of compression use reception: a manual butterdish drip a little engine oil in a nest of a spark plug and once again measure compression pressure.

• If indicators and are lower now norms, valves not as it should be.
• If indicators became higher, matter in piston rings and, maybe, in cylinders. The filled-in oil for a while worked as laying between the piston and walls of the cylinder so the compressed gas almost did not find a way out.

The test for loss of pressure (on tightness)

More exact results are yielded by the tightness test which some workshops can carry out. If the checked combustion chamber loses pressure, it is shown on a tester scale.

Larger place of leak can be determined by listening:

• Hissing in an exhaust pipe testifies to leaky closed final valve.
• The air effluence from the case of the air filter testifies to defect of the inlet valve.
• At defective laying of a head of the block of cylinders or a crack in a head of the block of cylinders compressed air arrives through the next nest of a spark plug or from an open broad tank with cooling liquid outside.
• The worn-out walls of cylinders directing pistons or piston rings pass pressure in a case, and it leaves an open maslozalivny branch pipe or a tube for the probe of measurement of level of oil.

Scrolling of the engine

Installation of the cylinder No. 1 in the top dead point of the moment of ignition

In the four-cycle engine the piston during four working steps two times come to the top full stop (TFS): once at ignition of the let-in mix, for the second time – after emission of exhaust gases, with the admission of fuel and air mix beginning right after it. Usually during various adjusting works the position of VMT of the cylinder No. 1 is required.

Dismantle of facing of the engine

Dismantle of facing of a klinovo-ridge belt

6-cylinder engine

The belt in the six-cylinder engine works as Poliklinova under facing at the frontal party of the engine.

Dismantle of a cover of a head of the block of cylinders