Checking the technical condition of the engine

In the case of reduction of engine power (if serviceable power systems and ignition) are checking cylinder compression (see. Sect. 3.1.3).

Determine the condition of the engine can also use the vacuum gauge. To obtain correct results, this method of verification is recommended to combine with other methods. Before testing is necessary to connect the hose of the vacuum gauge to the intake manifold, start up the engine and warm it up to normal operating temperature.

If the manifold pressure is 430-560 mm Hg. Art., and the gauge needle is at rest, the normal condition of the engine.

If the manifold pressure is significantly below 430 mm Hg. Art., and the gauge needle is fixed, then the following engine failure: damaged gasket between the intake manifold and the throttle body, vacuum hose is damaged, improperly installed ignition point or valve timing.

If the reading on the gauge below norm 80-200 mm Hg. Art. and his hand range, it is possible that the intake manifold gasket is damaged or faulty injection system.

If the pressure drops to 50-100 mm Hg. st., then returns to its original value with a certain frequency, it may indicate a valve damage. In this case it is necessary to measure the compression in the cylinders.

If the pressure drops, but not regularly, then the possible reason for this may be jammed valve or omissions in the ignition.

When constant engine speed to idle needle gauge fluctuates rapidly with changes in amplitude readings of about 100 mm Hg. Art., and from the exhaust pipe is black smoke - damaged valve guides. If the arrow quickly fluctuates with increasing speed - damaged the intake manifold gasket or cylinder head gasket, weakened valve springs, burned valves or have gaps in the ignition.

Small pressure fluctuations of about 25 mm Hg. Art. usually associated with failures in the ignition system.

When you swing the arrow with large amplitude - damaged cylinder head gasket or cylinder.

If the needle moves slowly in a wide range - clogged crankcase ventilation system, damaged the intake manifold gasket or seal between the throttle body and intake manifold.

Check how quickly restored the pressure in the intake manifold after full throttle. For this you need to turn to an assistant, who must be the way to press the accelerator pedal, and then release it. When you press the pedal pressure should fall almost to zero, and then increase by about 130 mm Hg. Art. above normal, and quickly return to normal at a steady engine speed to idle. If the pressure is slowly restored and its value goes through a maximum after closing of the throttle, this may indicate a fault of the piston rings. If the delay is longer, then blocked the exhaust system.