2.2. Diagnostics of the general mechanical engine failures
There are admissions of ignition during the operation of the engine on single turns
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Most often admissions of ignition of the engine result from violation of functioning of power supply systems and/or ignition. If it is not possible to find out a cause of infringement during failure diagnostics of these systems, check the following possible options: |
Leak of air through laying of the inlet pipeline takes place. Check, having missed the mark with oil or a moisture absorber pipeline joints at the working engine and listen to the hissing indicating a leak source.
Adjustment of valves (engines of 4.2 l) is broken. Check, in case of need make correction of gaps.
Integrity of laying of a head of cylinders is broken. Make check of compression pressure in cylinders, in case of need replace laying.
Takes place прогар plates of valves or their saddles in a head of cylinders. Check compression pressure, in case of need make capital repairs of a head.
Piston rings are broken or worn-out. Check compression pressure, in case of need replace rings.
Valvate springs weakened or are worn out. Uncover a head of cylinders and check a condition of valvate springs.
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For check of compression pressure cut off power system of ignition and act according to the instructions stated in the Section devoted to general settings of the engine (see the Head Nastroyki and routine maintenance). |
The valvate mechanism during the work publishes unusual noise
Adjustment of gaps of valves (engines of 4.2 l) is broken. Check, execute adjustment.
Valvate springs weakened or are broken. Uncover a head of cylinders and check a condition of valvate springs. In case of need make replacement.
Assemblies of yokes are worn-out or damaged. Replace defective components.
Hydraulic pushers (engines of 3.0 l) are faulty. Replace defective pushers.
The directing plugs of valves are worn-out. Execute capital repairs of a head of cylinders.
Working ledges of cams are worn-out. Check a condition of the camshaft, in case of need make replacement.
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Before removing the camshaft for survey of cams check pressure of oil and a condition of valvate springs and if are applied, hydraulic pushers. |
The noise published by bearings of the lower heads of rods take place
Oil supply is broken. Check oil level in the pallet of a case and a condition of the oil pump and reducing valve. Replace an oil filter.
The gap in bearings is excessive. Replace inserts, check a condition of conrod necks of a bent shaft, in case of need execute their pro-point.
Too liquid oil is filled, or there was its fluidifying gasoline or water. Replace motive oil, the gulf is fresher than the required grade. Try to reveal and remove the fluidifying cause.
Oil pressure fell. Check serviceability of the reducing valve, a condition of a spring. Also check serviceability of functioning of the perepuskny valve of an oil filter.
There was a shift of conrod bearings. Correct rods, in case of need make replacement of inserts.
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At malfunction of conrod bearings usually there is a metal knock which intensity is maximum at the movement of the car with a speed of 60 km/h with the closed butterfly valve. Before starting dismantling of the engine for the purpose of check of a condition of the lower heads of rods, check the level and a consistence of motive oil on the measuring probe. Also remove the sensor switch of pressure of oil and, having screwed the manometer on its place, measure pressure. |
The noise published by radical bearings (obvious) take place
Fastening of a flywheel weakened. Tighten bolts with the required effort.
Oil pressure fell. Check gaps in radical bearings. Check a condition of the oil pump and reducing valve. In case of need make recovery repair of the pump.
The axial side play of a bent shaft is excessive. Replace radical bearings.
There was an ovality of necks of a bent shaft. Pierce necks and replace bearings (on the repair size with belittling).
Oil supply is broken. Add oil in a case, having brought its level to the required value.
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Points out heavy, but stupid knock malfunction of radical bearings during the operation of the engine under loading. When weakening fixture of a flywheel the deaf or stupid knock arises during switching off of the engine. It usually is followed by vibration. |
The consumption of motive oil is excessive
Oil leak takes place. Check a condition of laying and epiploons. In case of need make replacement.
Maslootrazhatelny caps of cores of valves are damaged or worn-out. Replace defective caps.
The gap of landing of cores of valves in the directing plugs is excessive. Replace guides and/or caps.
Piston rings are worn-out or broken. Replace rings on all pistons. Piston rings are too hardly put or jammed in the flutes. Replace rings, clean flutes.
Cylinders, pistons and piston rings are excessively worn-out. Pierce and/or an otkhoninguyta cylinders, replace pistons and/or piston rings.
Compression rings are incorrectly established, oil scraper rings are broken or jammed. Make replacement.
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Before starting check of the engine on existence of signs of leak of oil, it should be cleared and degreased carefully. Warm up the engine up to the normal working temperature. Enclose on the earth directly under the engine pure (it is desirable white) a leaf of a cardboard for identification of sources of leak of oil. |
Pressure of motive oil fell
Oil level fell in the case pallet. Check, in case of need add.
Too liquid oil is filled, or there was its fluidifying. Replace oil and remove the fluidifying cause if that took place.
The reducing valve is jammed, or its spring is broken. Remove the cause of jamming or replace the broken valvate spring.
The gap in bearings is excessive. Replace inserts, or (in case of need) pierce necks of a bent shaft.
Wear of components of the oil pump is excessive. Make recovery repair, or replace the pump.
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If the car is not equipped with the oil pressure measuring instrument, remove the sensor switch of pressure of oil and screw the manometer on its place. Measure pressure of oil both at cold, and at the hot engine. At the faulty oil pump or the reducing valve pressure will be low in both cases. however, if defect of bearings takes place, oil pressure on the cold engine will be rather high whereas after warming up considerably falls. |
The engine is not turned
The starter is jammed. Remove a starter. Check a state and (in case of need) replace the damaged drive and/or a gear wreath of a flywheel.
The engine klinit with a simultaneous overheat. Remove the engine and disassemble it. Check a condition of internal components, make necessary replacements.
In cylinders moisture at the expense of a water podsasyvaniye to the highway of an intake of air (got for example during a crossing through the river). Turn out spark plugs and dry cylinders.
Water gets to cylinders through laying of a head of cylinders or a crack in a head/block body. Remove a head of cylinders. If cooling liquid filters through laying, check planeness of the interfaced surfaces of a head and the block. In case of need make a pro-point. At detection of cracks the head/block should be replaced.
Damage of a bent shaft or components of conrod and piston groups takes place. Remove and disassemble the engine. Examine components, make necessary repair / replacement.
Integrity of a plate of the valve owing to an overheat or fatigue deformation is broken. Remove a head of cylinders and check a condition of its components. Make necessary recovery repair or replacements.
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Frequent jamming of the drive of a starter on a gear wreath of a flywheel can be caused by a bend of a shaft of an anchor or damage of teeth of a driving gear wheel and/or wreath of a flywheel. The condition of a gear wreath of a flywheel can be checked through an adjusting opening a starter after removal of the last. If water got to cylinders suddenly, in the course of a water crossing or for other similar reason, there can be a deformation of rods. However, if clear water got to the stopped engine, its start can be made without special complications. |
Turn out candles and cut off power system of ignition as it is described in the Section devoted to check of compression pressure (setup of the engine) in the Head Nastroyki and routine maintenance.
Turn the engine manually, having pushed out from it as much as possible water.
Then turn the engine a starter - try not to bend over the engine block as water can be pushed out through candle openings with a decent pressure. Check motive oil, the distributor, the carburetor, the air cleaner, the fuel filter and the fuel tank for existence of traces of presence of moisture in them. If moisture is not found, dry and screw to the place of a spark plug and start the engine.
When jamming the engine as a result of an overheat owing to falling of level of cooling liquid bearings, pistons, etc. components unambiguously fail. Though sometimes the engine also manages to be started successfully after an ostuzheniye and replacement of oil and cooling liquid, such deviations as the raised oil consumption, oil pressure drop usually are soon shown, the level of noise during the operation of the engine, etc., depending on degree and the nature of damages increases.
At infiltration of cooling liquid in cylinders through laying of a head, or if compression pressure in two next cylinders low, is extremely important to check carefully interfaced surfaces of the block and a head of cylinders for planeness violation. Through thinnesses of laying or a crack in the head/block the amount of water, sufficient for engine failure from a provorachivaniye, can filter into cylinders. Usually such situation is followed by difficulties at start, admissions of ignition, a steam-out from an exhaust pipe, and also falling of level of cooling liquid.
Leak of gases in the cooling system can be revealed by removal of a cover of a radiator and observation of bubbles in the top tank of a radiator at the engine working with turns of bystry idling or without removal of a cover of a radiator on excessive inflow from a broad tank.