3.2. Search and elimination of malfunctions in operation of the engine
By means of the given techniques of search and elimination of malfunctions in operation of the engine it is possible to find the most probable causes of malfunctions in operation of the engine. These operations cover components of fuel system, system of ignition and mechanical systems which can become the reason of this concrete malfunction, and then ways of elimination of these malfunctions are given in the logical sequence.
As the important sign signaling about malfunction of the engine during the movement serves constantly burning or quickly lit control lamp "The engine will demand service soon". At the same time it is necessary to check the malfunction code which is stored in a computer control system for the engine or in electronic system of diagnostics. The description of signs of each malfunction is provided in the management and on the basis of the found malfunctions it is necessary to choose the correct sign. The sign of malfunction is given together with the description of malfunctions.
In certain cases the used terms can turn out unfamiliar and therefore that many of them are interchangeable, it is necessary to analyse the most frequent use of each term and then to define its value. If value of the term is not clear and the concrete sign is not clear, then the procedure of search and elimination of malfunctions cannot use. It is important to remember the following two facts.
1. Procedures of search and elimination of malfunctions are provided for diagnostics of malfunctions of the engine which some time worked normally, and then aging and wear created a new situation.
2. It is impossible to capture all possible reasons of malfunctions, especially those which influence the content of emissions of harmful substances. If performance of actions for elimination of malfunctions does not lead to malfunction disappearance, means or the wrong sign was chosen, or it is necessary to carry out more detailed analysis. Practically all from the given signs of malfunctions can be caused by worn-out or faulty details, such as spark plugs, wires of system of ignition, a cover and a rotor of the distributor of system of ignition, and also fuel and air filters.
Searches of elimination of mechanical malfunctions
Information on diagnostics given below covers usually found mechanical malfunctions and ways of their elimination. At the correct diagnostics malfunction can be eliminated by adjustment, repair or replacement of details. The sequence of action necessary for this purpose is given in the corresponding chapter of this manual.
The raised oil consumption
The raised consumption of oil can be caused by one of the following reasons:
– leakage of the lubrication system. Tighten threaded connections and/or replace if it is necessary, laying and sealing rings;
– the wrong measurements of level of engine oil by means of the index of level of oil. When determining level of oil put the car on the flat horizontal platform and wait sufficient time that oil flew down in the pallet;
– too low frequency of rotation of a bent shaft idling. If the frequency of rotation of a bent shaft of the engine idling is not controlled by the electronic block, adjust the frequency of rotation of idling according to requirements;
– there does not correspond the type of the installed sensor of pressure or pressure sensor is faulty;
– the wrong type of the installed manometer or the faulty manometer which needs to be replaced;
– inappropriate viscosity of engine oil or liquid oil. Fill in oil for the corresponding season, or replace the oil diluted because of hit of moisture or not burned down fuel mix;
– the worn-out or polluted oil pump. Replace the oil pump;
– the polluted oil filter. Replace an oil filter;
– the mesh filter on a reception branch pipe of the oil pump unscrewed or is hammered. Clear and/or wash out the mesh filter;
– a side opening in a reception branch pipe of the oil pump. Replace a branch pipe;
– viscosity of engine oil does not meet the specification. Use oil of the SAE standard for the corresponding temperatures of operation;
– the long movement at big speeds or with the trailer usually leads to increase in a consumption of oil;
– malfunction in system of compulsory ventilation of a case;
– wear of maslootrazhatelny caps and/or the directing plugs of valves or lack of maslootrazhatelny valves. Chisel the directing plugs and establish the valve of the repair size and/or new maslootrazhatelny caps;
– badly earned extra, worn out or broken piston rings. Let's new piston rings get used for some time. If necessary replace the broken or worn-out piston rings;
– wrong installation of the piston or its wrong size.
Low pressure of oil
Low pressure of oil can be caused by the following reasons:
– the increased gap in bearings. If necessary replace the bearing;
– cracks, a time or traffic jams in channels of the block of cylinders. Repair or replace the block of cylinders;
– caps lubrication systems are absent or are incorrectly installed. Establish caps or if necessary replace.
Noise in the gas-distributing mechanism
Noise in the gas-distributing mechanism can be caused by any of the listed below reasons:
– low pressure of oil. Remove the cause;
– weakening of fastening of levers of valves. Check and if necessary eliminate;
– worn-out lever and/or pusher of the valve;
– breakage of springs of the valve;
– jamming of valves;
– worn-out, dirty or faulty pushers of valves. Clear of dirt, check and if necessary replace;
– worn out or with defects the camshaft. Replace the camshaft;
– guides of valves are worn-out.
Search and elimination of the reasons causing knock in the engine
The knocks in the cold engine proceeding 2–3 min. and/or amplifying at increase of loading
• The flywheel touches a casing. Adjust installation of a casing.
• The balance weight or a pulley of the drive unscrewed or broke.
• The increased gap between pistons and cylinders. Chisel the cylinder and an otkhoninguyta under the repair size and replace pistons. The knock of pistons on the cold engine usually disappears after grinding in. The knock of pistons of the cold engine disappearing in 1,5 min. is admissible.
• The rod is bent.
The strong knock of the heated-up engine arising under loading
• The balance weight or a nave of a pulley is broken. If necessary replace.
• Weakening of bolts of fastening of the automatic transmission.
• Belts of the drive of the service equipment are drawn. Replace or adjust a tension.
• The exhaust pipe concerns the surface of the road. Fix an exhaust pipe.
• A crack in a flywheel.
• The increased gap in radical bearings. If necessary replace.
• The increased gap in conrod bearings. If necessary replace.
Easy knock during the operation of the heated-up engine
• A detonation in engine cylinders.
• Check installation of a corner of an advancing of ignition and quality of fuel.
• Weakening of bolts of fastening of the automatic transmission.
• Violation of tightness of a final collector. Tighten bolts and/or replace laying.
• Gaps of conrod bearings are increased. If necessary replace bearings.
Knocks at launch of the engine, the lasting only several seconds
• Oil of inappropriate viscosity.
• Fill in oil which viscosity corresponds to service conditions.
At the idle engine some the valve will be in open situation. Spring pressure upon the hydraulic mechanism of adjustment of a gap of the valve will lead to reduction of hydrostatic pressure. Repair is required, only if this defect is present constantly.
• The axial side play of a bent shaft is increased – replace the persistent bearing.
• The gap in the forward radical bearing is increased. Replace worn-out details.
Knocks of the heated-up engine idling
• Insufficient tension or wear of driving belts. If necessary pull and/or replace belts.
• The bearing of the compressor of the conditioner or the generator is damaged. If necessary replace.
• Malfunctions in the gas-distributing mechanism. If necessary replace the failed details.
• Viscosity of engine oil does not conform to requirements. Fill in oil with the viscosity corresponding to a season of operation of the car.
• The gap in a piston finger is increased. Replace a piston finger and the piston.
• The rod gap is increased. Check gaps and if necessary replace a rod.
• An insufficient gap between the cylinder and the piston. The cylinder also install to Otkhoninguyta the new piston.
• The counterbalance of a bent shaft unscrewed. Tighten and/or replace worn-out details.
• The piston finger is displaced the party from an axis. Install the piston correctly.
The engine overheats
1. Leakage of the cooling system of the engine, leakage in the cooling system of gearbox oil. Check for existence of a leak and eliminate it. Check a broad tank, a hose and a stopper of a mouth of a radiator.
2. The driving belt slips or is damaged. If necessary to replace a belt or a natyazhitel.
3. The thermostat does not open. Check and if necessary replace.
4. Operation of the electric fan of a radiator is broken.
5. A leak through laying of a head of cylinders. Check and if necessary eliminate.
During the operation of the engine the control lamp of low pressure of engine oil idling burns
1. The pipeline of circulation of a cooler of oil or the pipeline of a cooler is polluted.
2. The low pressure created by the oil pump.
Check of a compression
The inspection given below is carried out before dismantling of the engine. It is used for confirmation of need of dismantling and capital repairs of the engine and restoration of its parameters.
Disconnect the VAT socket from the distributor of ignition or the block of ignition.
Results of check of a compression in cylinders of the engine allow to judge a condition of group of details in the top part of the engine (pistons, piston rings, valves and laying of a head of the block of cylinders). Namely, reduction of a compression can be caused by leakage of combustion chambers owing to wear of piston rings, damage of plates and saddles of valves, a burn-out of laying of a head of the block of cylinders.
Clear sites near spark plugs for what blow compressed air (in the absence of the compressor blow sites automobile or even bicycle, the pump). It is necessary to exclude hit of dirt in cylinders at measurement of a compression.
When checking a compression the engine has to have normal working temperature, the butterfly valve has to be open, all spark plugs are turned out, and the rechargeable battery – completely or is almost completely charged.
Insert компрессометр into an opening for a candle.
Include a starter and turn a bent shaft at least on seven steps of compression, monitoring indications of a kompressometr. The minimum indication of the manometer has to be not less than 689 kPa.
On the serviceable engine pressure has to increase quickly. Low pressure after the first piston stroke and slow increase at the subsequent steps of compression indicates wear of piston rings. If after the first piston stroke pressure low and at the subsequent steps of compression does not increase, then leak in valves or leakage of laying of a head of the block of cylinders is the reason (also formation of cracks in a head can be the reason). Decrease in a compression can be also caused by deposits of a deposit on reverse sides of plates of valves. Write down the greatest value of a compression.
Repeat the procedure of measurement for other cylinders and compare results to specifications.
If a compression in cylinders below minimum admissible value, through an opening for a candle enter into each cylinder of a little engine oil, then repeat check. If after oil introduction the compression raised, then it is possible to draw an unambiguous conclusion that piston rings are worn-out. If the compression increased slightly, then leak happens via valves or laying of a head of the block of cylinders. Leak via valves can be caused by a burn-out of saddles and/or working edges of valves, and also deformation of cores of valves or formation of cracks on them.
If the compression equally low only in two next cylinders, then is the most probable cause a laying burn-out between these cylinders. As confirmation emergence in combustion chambers or the oil pallet of traces of cooling liquid is possible.
If value of a compression exceeds nominal rate, so the combustion chamber is covered with deposits of a deposit. In this case the head of the block of cylinders should be removed and removed a deposit.