| 1. Measurement of depression is reliable and rather cheap way of diagnostics of the engine. According to indications of the vacuum gage it is possible to receive idea of a condition of piston group, tightness of laying of a head of the block of the cylinders which are soaking up and final collectors, correctness of adjustment of the engine, etc. |
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2. The vacuum gage joins zadrosselny space to measure pressure directly on a soaking-up collector. It is not necessary to connect the vacuum gage to hoses of auxiliary units. |
| 3. Vacuum diagnostics is expedient for uniting with other methods of diagnostics. |
| 4. Initial factors on which indications of the vacuum gage are analyzed and the most exact conclusions about an engine condition become, absolute instrument reading and nature of movement of an arrow of the device (dynamics of indications) are. |
| 5. Before the beginning of tests completely warm up the engine, block wheels. |
| 6. Check the vacuum gage indication. On the serviceable engine idling, the vacuum gage should show depression of 430-560 mm Hg, and the arrow of the device should be almost motionless. |
| 7. If vacuum gage indications on 75–200 mm Hg are lower normal and are unstable (the arrow twitches), it indicates a leak in laying on an entrance of a soaking-up collector, or on violation of tightness of a nozzle. |
| 8. If the arrow regularly deviates on 50–100 mm Hg, the reason is the leakage of valves. Check a compression in engine cylinders. |
| 9. If the arrow irregularly deviates towards low indications, or shaking shows low depression, the reason is the increased resistance to movement of valves, or ignition interruptions. Check a compression in cylinders and examine candles. |
| 10. If idling the arrow quickly fluctuates within 100 mm Hg, and operation of the engine is accompanied by a smoke from the exhaust silencer, directing plugs of valves are worn-out. If the arrow quickly fluctuates with simultaneous increase in turns of the engine, it is necessary to check tightness of laying of a soaking-up collector, elasticity of springs of valves. Such indications also can be caused by a burn-out of valves and ignition interruptions. |
| 11. Weak fluctuations of an arrow within 20–30 mm Hg indicate unstable work of ignition. |
| 12. At big fluctuations of an arrow check a compression in cylinders. |
| 13. Slow change of depression in a wide range indicates a contamination of system of ventilation of a boat, abnormal structure of a mix, and also on leak in collector laying. |
| 14. Finish engine turns to 2500 rpm and release a pedal. Indications of the vacuum gage should fall almost to zero, then increase and exceed the control indications corresponding to stationary idling, approximately on 125 mm Hg then depression should be restored at former level. The different behavior of depression indicates wear of piston rings. If these indications change too slowly, check purity of channels of an exhaust system (especially converter). |