What are the peculiarities of the engine defectology and what is it
Engine defectology is carried out for cars that have significant mileage. The result of the process depends on the degree of wear of parts and mechanisms that are components of the ICE.
What is an engine defectology
Nodes and parts of the car are subjected to intense wear and tear. At the same time, the depreciation occurs unevenly, especially this applies to the engines of cars, which are subjected to intensive operation.
Important! Defective inspection – the process of expert evaluation and identification of causes, provoking the failure of the power unit or individual nodes and mechanisms.
The engine is disassembled into separate elements beforehand. The specialist performs a visual inspection and the necessary measurements. The condition of all important parts is monitored for obvious and hidden defects.
There may be different reasons that prompted the event. One of them is the need for a preliminary in-depth inspection of the internal combustion engine just before the scheduled overhaul. An additional incentive for disassembly and evaluation of the condition is the evaluation of the possible damage in the event of a sudden breakdown, for example, when the timing belt broke off, a connecting rod came off or the engine got jammed.
Under natural conditions, there is relatively predictable and predictable wear of working parts. With time piston rings wear out, the mirror of the combustion chamber deforms, valve seats wear out, etc.
Engine resource engineers calculate the engine resource for a certain mileage, during which the wear and tear will occur and the performance of consumables will decrease. However, abnormal situations occur, when the operating parameters are reduced quite sharply. A thorough visual and metric inspection helps to detect a drop in service life, so defectoscopy is often referred to diagnostic activities.
How a power unit is inspected
Before you start, you need to take care of good lighting and the necessary set of measuring tools. It is desirable to have lamps for local illumination, apart from general lighting, which helps to identify small defects.
Carry out the defectology of the dismantled engine parts can be carried out in parallel with the dismantling operations. Masters involved in the repair of engines, can at this time to assess the condition of each part and unit, which will make it possible to make a generalized primary conclusions.
It is worth immediately discarding parts that are too badly damaged or elements that are not designed for rebuilding. Parts with no visible defects are put aside on the other side. This group is sent to the next stage of diagnostics.
The selected elements are checked for technical and geometrical characteristics:
- linear overall dimensions are measured;
- inside and outside diameters are monitored;
- the surface roughness is checked against the standard, etc.
It is necessary to take into account that the dimensions of the parts have a tolerance field, within which the dimensions are located. It is recommended to fill in during the process the defect list, in the table of which names, dimensions and possible necessary works on replacement or restoration of initial characteristics are entered.
Particular attention must be paid to the cylinder block, since it is a basic part of the engine. The detected problems must be described and prepared for elimination. In the process of inspection, faults are identified:
- scoring; ;
- mechanical and thermal deformations;
- Faults in the threaded holes, etc.
To find cracks which might be caused by antifreeze or oil in the cylinders through the jackets, you can use crimping of the block. Oil or temp plugs are also checked for continuity during defect inspection. Cylinders inside are measured with a gauge, which will reveal the possibility of further operation of the block.
Attention is paid to cylinder head defectology. The main work is to identify the quality of the valve seats and deformation of the mating plane with the block. Also the holes for the camshaft bearings must be in order.
Inspection of the shaft is to measure the diameter on all working areas. Checked not only the diameter, but also the ovality of the neck, determining the largest and smallest parameter. Runout measurements are taken in each area.
All critical deficiencies identified should be eliminated. If repairs are possible, we carry out repair work, and otherwise it is necessary to replace the damaged parts and units with new ones. This will prolong the operating life of the car, as well as ensure safety for the car owner.
What is an engine defect inspection: features of this procedure
Let’s start with the fact that engine defectology – a procedure that involves preliminary disassembly of the power unit, after which the inspection of parts is carried out, as well as their measurements for comparison with the nominal parameters.
Based on the data obtained, the decision is made about which parts need to be completely replaced, and which parts can still be restored or repaired for further operation. The hidden cause of these or those damages, which take place in a particular internal combustion engine, is also determined.
In other words, the master gets a general idea about the state of the engine and the degree of damage, and is able to roughly estimate the amount of work and how much it costs to repair the engine, already after the defektovki. Let’s take a closer look at what engine defectology means, as well as how this procedure is performed.
Engine defectovka: what is the procedure of engine defectovka
As already mentioned above, engine defectovka is needed to assess the overall state of the internal combustion engine, as well as in order to establish the reasons for which there was a partial or complete failure of the power unit. The very name of the procedure comes from the word defect, that is, defektovka engine needed to identify various apparent and hidden defects.
There may be many reasons for defectovki, starting from the necessity of a preliminary in-depth examination of the engine before the scheduled overhaul and ending with the assessment of damages after the unforeseen breakdowns (engine cramping, crank rod breakage, hydrostroke, timing belt breakage etc.).
An engine normally wears out naturally, and this wear is characterized by a characteristic evenness. Piston rings gradually wear out, the cylinder mirror is damaged, the shape of the cylinder itself changes, valve seats are broken, plain bearings, crankshaft necks are worn, etc.
It turns out that it is appropriate to say that the resource of the engine with high mileage is simply exhausted. However, it also happens that the power plant gets to the defectology much earlier than expected. In this situation, it is especially important not only to detect and qualitatively eliminate the existing damage, replace individual parts, etc., but also to determine the root cause of this breakdown.
The fact is that if you do not accurately determine the original cause, then after repair or reassembly the engine can fail again, and sometimes this happens very quickly. It turns out that the fault detection can be considered not only as an evaluation, but also as a diagnostic procedure, which allows you to determine exactly what caused the occurrence of this or that malfunction.
How is the defectology of the power unit performed?
Having understood why it is necessary to defect the engine, let us now consider the procedure itself. As a rule, engine defectology can be divided into several main stages.
- At the very beginning, the defectology of various parts begins to be carried out in parallel with the process of disassembly of the power unit. An internal combustion engine repair specialist visually assesses the condition of each part that is removed from the motor, after which certain conclusions can already be drawn based on such a preliminary assessment.
- Then the master puts aside the parts that are badly damaged or irreparable. After that, these parts should be replaced by new ones, according to the list. Another group is formed next to it, which includes parts that are still rebuildable or have no noticeable damage.
- Parts that are collected in the second group are elements for the second stage of defectology. Next, their dimensions and parameters are carefully measured, after which the data obtained are compared with the nominal. Experienced craftsmen specially keep a so-called defectovo-list, which forms a list of restored parts and those elements that have not been changed at all in the framework of the current repair. Such a list, when the next repair becomes necessary, makes it easier for the next part to be defective.
Defective inspection of the engine cylinder block
As you know, the cylinder block is actually the main part of the entire engine. Moreover, the BC is a numbered part, since the engine number is made exactly on the block. In other words, the block must be defective particularly carefully, as its complete replacement involves in the future certain difficulties on the legal side.
- Defective inspection of the engine involves inspecting the cylinder block. At the very beginning, a visual inspection of the block is carried out to detect scoring, cracks on the cylinder mirror, between the threaded holes in the cylinder-head mounting locations.
- If there was noted a leakage of engine oil into the antifreeze or antifreeze into the oil, then there is an additional block pressure test to detect cracks in the oil or cooling ducts;
- Then the temperature and oil plugs are checked for continuity, and the check also affects the crankshaft bed, main caps (crossheads), etc.
- The next step is to measure the cylinders with special tools (numeraire, etc.). The next step is to measure the cylinders with special tools (gauges, etc.) to determine if the cylinder is suitable for further operation.
- The cylinder blocks with replaceable liners are inspected in the area of the liner seating belt and the condition of the cylinder-head mounting studs, etc., is assessed in parallel.
As you can see, internal combustion engine repair specialists pay maximum attention to the cylinder block. The block is carefully inspected for cracks and deep scoring in the cylinder mirror area, and the oil and other channels are also checked.
If the block has such damage, then a decision is made on the possibility and expediency of repairing these or those defects, boring of the cylinders, cylinder liners, etc. The block to be repaired is then washed and the oil cavities are opened and rinsed.
We also recommend reading the article about what is an engine overhaul of the car. From this article you will learn about the peculiarities of the overhaul, which operations involve such a repair of the internal combustion engine, etc.
Then the BC is ground to repair dimensions or liner to restore the necessary parameters (depending on the type of block, the material of its manufacture, the degree of damage, etc.). It is very important to perform all operations correctly, as well as to observe the peculiarities of the technological process.
For example, specialists pay special attention to the honing of the cylinders. Honing allows you to achieve proper operation of piston rings, get rid of increased oil consumption, etc.
What’s the Bottom Line
Given the above information, it becomes clear that only after conducting a defectoscopy can you really assess the condition of the engine. Based on the results it becomes possible to make a preliminary estimate, that is more accurately determine how much it costs to overhaul the engine or to rebuild this or that motor.
In this case before making an independent decision to purchase a contract engine, in some cases it is recommended to conduct inspections, in order to have a clear idea of the wear degree, the damages and the possibility of repair in relation to this or that particular engine.
For example, today specialists are successfully restoring even aluminum blocks, and initially the possibility of repair of such blocks was not provided by the manufacturer. In other words, there is no factory technology for overhaul, the blocks themselves are unrepairable, there are no official factory solutions for overhaul of such engines with aluminum blocks.
Without going into details, in practice the issue is solved with the help of overhauling the aluminum block. In many cases a correctly performed operation provides a sufficiently large “margin” of safety to the engine, that is the power unit is able to go after the repair at least another 100 thousand km.
We also recommend reading the article about what is liner fitting of the cylinder block. From this article you will learn about liner cylinder block, as well as about the peculiarities of this procedure, various nuances, advantages and disadvantages.
Given the fact that we are talking about the engines on rather expensive cars (Range Rover, BMW, etc.), defektovka and overhaul of such an engine by non-factory technology may be more profitable and reliable solution than swap the engine for the same contract used unit. The thing is that installing used motor you need to be ready to the fact that its condition is not known for sure.
Also, a similar power unit does not differ from the old motor, that is, in the foreseeable future the same problems may occur that caused the failure of the already existing engine.