BMW 3 series E30

Since 1983-1994 of release

Repair and car operation

3.2.6. Diagnostics of the engine with the help вакууметра

THE GENERAL DATA

Depression measurement is reliable and rather cheap way of diagnostics of the engine. Under indications вакууметра it is possible to receive representation about a condition of piston group, about tightness of linings of a head of the block of the cylinders which are soaking up and final collectors, correctness of adjustments of the power supply system of the engine and release of the fulfilled gases, throughput of the fulfilled gases, a condition of valves (them залипании or a burn-out) and springs of valves and also to check up correctness of adjustment of the moment of ignition and preservation of phases timing at engine work.

Unfortunately, indications вакууметра are difficult for interpreting and results of the analysis of indications can be erroneous, therefore, vacuum diagnostics expediently to unite with other methods.

Initial factors on which indications вакууметра are analyzed and the most exact conclusions about an engine condition become, the absolute instrument reading and character of movement of an arrow of the device (dynamics of indications) are. A majority scale вакууметров проградуирована in mm. рт. A column. In process of depression increase (and accordingly pressure drop) the instrument reading increases. On each 300 m above sea level absolute indications вакууметра will differ approximately on 25 мм.рт.ст.

Attach вакууметр directly to a soaking up collector, but not to other apertures through which the vacuum, by the channel of certain length separated from a collector (for example, to apertures before throttle заслонкой) is created.

Before the beginning of tests completely warm up the engine. Block wheels and put the car on a manual brake. At position of the lever of a gear change in neutral position (or in position Park on cars with automatic transmission) start the engine and leave to idle.

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The prevention

Before engine start carefully check up a condition of blades of the fan (presence on them of damages or cracks). In an operating time of the engine do not bring a hand too close to the fan, hold the device on sufficient removal from the fan and do not stand on one line with rotating крыльчаткой.

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Check up the indication вакууметра. On the serviceable engine вакууметр should show depression 430–560 мм.рт.ст., and the arrow of the device should be almost motionless.

More low the description of character of indications вакууметра and techniques of definition of a condition of the engine on their basis follows.

And. Too low level of depression usually specifies on негерметичность linings between a soaking up collector and the chamber throttle заслонки, a vacuum hose, and also in too later ignition or for the wrong moment of opening and closing of valves. Before removing covers of a gear belt and to check up combination of adjusting labels check up installation of ignition by means of a stroboscope and eliminate all other possible reasons.

. If indications вакууметра on 75–200 мм.рт.ст. Below normal also are unstable (the arrow twitches) it specifies in a leak in a lining on an input of a soaking up collector or on malfunction of an atomizer.

Century If an arrow regularly deviates on 50–100 мм.рт.ст., the reason is негерметичность valves. For acknowledgement of this conclusion check up a compression in engine cylinders.

The Arrow irregularly deviates towards low indications, or shaking shows low depression. A plausible reason is the raised resistance to movement of valves, or faults in work of cylinders. Check up a compression in cylinders and examine candles.

д. If idling the arrow quickly fluctuates within 100 мм.рт.ст., and engine work is accompanied by a smoke from the muffler directing plugs of valves are worn out. For check of this conclusion it is necessary to conduct tests of chambers of combustion for tightness (with air rating). If the arrow quickly fluctuates and the increase in turns of the engine it is necessary to check up tightness of a lining of a soaking up collector, elasticity of springs of valves is simultaneously observed. Such indications also can be caused a burn-out of valves and faults in work of cylinders (ignition failures).

е. (Within 20–30 мм.рт.ст.в both parties) specify weak fluctuations of an arrow in unstable work of ignition. Check up all provided installations and adjustments, if necessary connect to the engine the analyzer of system of ignition.

. At the big fluctuations of an arrow check up a compression in cylinders, or conduct tests for tightness as causes of defect can be the idle cylinder, or infringement of tightness of a lining of a head of cylinders.

з. If instrument readings slowly vary in a wide range check up cleanliness of pipelines of system of compulsory ventilation картера, correctness of adjustment of a gas mixture, tightness of linings of the case throttle заслонки, or a soaking up collector.

And. Sharply open throttle заслонку and when engine turns will reach 2500 about / mines release заслонку. Заслонка should come back slowly in a starting position. Indications вакууметра should fall almost to zero, then increase and exceed the control indications corresponding to stationary idling approximately on 125 мм.рт.ст., then depression should be restored at former level. If depression is restored slowly, and at sharp opening заслонки excess of the control indication is absent, the reason deterioration of piston rings can be. At the slowest restoration of depression check up cleanliness of a final path (as a rule the muffler or каталитического the converter). The most simple way of such check consists in disconnection of an exhaust path before a suspicious site and in test repetition.