Modern diagnostics of powertrains have gone far beyond listening to noise with a stethoscope or measuring compression. cylinder-piston groupMechanics use optical devices that allow you to literally look inside a working or stalled motor, a method often called endoscopy or video defection, has become the gold standard in assessing the residual life of the engine before buying a car or in identifying the causes of increased oil consumption.
Many car owners mistakenly believe that the absence of errors in the dashboard guarantees the perfect health of the engine. defects, such as microcracks in cylinder walls or rings that have begun to occur, are often not fixed by electronics until the moment of serious failure. visualization Through the candle hole becomes critical to prevent major repairs.
This procedure does not require a complete disassembly of the engine and can be done quickly enough. In this article, we will discuss in detail how to use the camera to inspect the cylinders, what to look for when analyzing the image, and what tools are needed to obtain a good picture, you will learn how to distinguish normal charcoal from signs of serious malfunction.
What is an endoscopy of the engine and why it is needed
Engine endoscopy is a non-destructive testing method that allows you to assess the technical condition of the internal cavities of the unit without dismantling it. videoendoscope It's a flexible or rigid probe with a miniature camera and a backlight at the end, and it's transmitted to a smartphone or tablet screen.
Why is that? Standard diagnostics, like compression measurement, only give averages of the tightness of the combustion chamber. They don't show that the compression chamber is tight. physicality And the endoscope is a real picture, of bullies, of hon-risk, of piston and valve integrity, and this is especially true for today's direct-injection motors, where problems can go up rapidly.
Use an endoscope with a rotary head (up to 180 degrees) - this will allow you to inspect not only the walls of the cylinder, but also the space under the piston, as well as the back side of the valves, which is impossible to do with a direct camera.
The method is also indispensable when buying a used car, and the seller may claim that the engine "did not open", but the camera will show traces of the car. sleeve Or replacing pistons if they're not good, and using an endoscope, you can also easily detect foreign objects that have fallen into the cylinder or the remains of gaskets after inept repairs.
Equipment required for video defects
It's not enough to buy the cheapest camera on the market to make a good diagnosis, and the quality of the image and the control capabilities directly affect the accuracy of the diagnosis. boroscopeWired models are more reliable transmitters and do not require constant recharging during long periods of operation.
The most important parameter is the diameter of the probe. For most gasoline engines, the diameter is considered optimal. 5-6 mmDiesel engines or engines with small candle wells may require thinner models with a diameter of 3.5-4 mm, however, they often have a lower matrix resolution.
The following set of tools and materials should also be prepared:
- 🔦 Powerful LED lighting at the end of the probe - allows you to illuminate the darkened sections of the cylinder without using an external flash, which creates glare.
- 🧹 compressor
- 🧴 Carburettor cleaner Sometimes it is required to wash off a dense layer of coar before examining the walls.
- 📱 Display device - Smartphone or tablet with a high-quality screen for detailed study of the picture in high resolution.
☑️ Testing of diagnostic readiness
Preparation of the engine for inspection through the candle hole
Before you enter the camera, you need to properly prepare the engine. hot-engineWhen he's been in the works for at least 10 to 15 minutes, the oil film is better at covering the walls, and the piston rings are in the working position, which gives a more realistic picture of the gaps.
The first step is to twist the spark plugs, and it's important to be careful not to drop any grains of sand into the cylinder, and around the candle wells, you need to carefully remove dust and dirt with compressed air, and if there is oil left in the wells, it is advisable to remove it with a syringe or pear so that it does not drip on the camera when diving.
⚠️ Warning: Never run a diagnostic on a working engine! A spinning crankshaft and rod can instantly destroy an expensive camera, and debris will hit the cylinder, causing bullies.
If the purpose of the inspection is to look for the cause of trifling or ignition failures, it makes sense to mark each candle and insert the camera into the cylinder where the problem occurred. cylinder-full They compare their state with each other.
For a better view, sometimes you need to turn the crankshaft with a starter, and this should be done with the candles twisted out and the coils or nozzles disconnected so that the engine does not start. Short-term scrolling will help you see the state of the cylinder from different angles and evaluate the operation of the piston rings.
Inspection technique and camera navigation
The insertion of the probe into the cylinder must be smooth, without the use of force. The camera is usually inserted through the spark plug hole. To get a full view, you need to slowly rotate the probe around its axis and change the angle of inclination of the head (if the design allows). work-surface.
There are several key areas to look at. The top of the cylinder (the zone of compression rings) is often covered with soot that can be washed off with a cleaner for better visibility. The middle and lower parts should have a clear khon grid. If khon has worn off completely, this is a sign of a cleaner. wear-and-wear or poor repairs in the past.
For detailed examination of hard-to-reach areas, such as the space under the piston or the valve area, use the camera rotation function. macro-imaging Or zooming, which allows you to see the microcracks, so you can record video of the entire inspection process, so you can later, in a quiet environment, examine frame by frame.
How to distinguish a shadow from a defect?
When the angle of light changes, shadows change shape and position, while physical defects (blowers, cracks) remain unchanged. Use this property for accurate diagnosis.
Pay special attention to the condition of the piston skirt and the area of the rings, if you see vertical stripes or furrows on the walls, these are the ones that are the most important. bullyIn diesel engines, through the candle hole (or the nozzle hole), you can also assess the condition of the valve plates for burnout.
Image analysis: What can be seen inside
The interpretation of what you see requires some knowledge. The normal state is that there is a uniform, thin layer of sofa on the piston and a clearly distinguishable holon net on the cylinder walls. The wall color can vary from silver to dark gray depending on the type of fuel and additives used.
However, there are signs that should alert any specialist, including:
- 🔴 Vertical scratches (bobbers) Deep furrows on the cylinder mirror, often accompanied by the destruction of the piston.
- 🔴 Traces of overheating Melting of the edges of the piston, changing the color of the metal (browning) or the appearance of "dry" spots without an oil film.
- 🔴 Valve raid - a thick layer of intake valves (relevant for direct injection motors), which can interfere with normal gas exchange.
- 🔴 Foreign objects - pieces of metal, fragments of rings or even forgotten rags that fell into the combustion chamber.
Special attention should be paid to the state of oil-ringIf you see through the gap between the piston and the wall that the grooves are full of coke and the rings are not moving, that's the direct cause of the oil collection, and sometimes you can save the situation by decoking, but often you need mechanical cleaning or replacement of the pistons.
Having even one deep bully in the top dead point (BMT) is often a reason to give up buying a car or planning an engine overhaul.
Typical defects and their effect on the operation of the engine
Every defect that the camera detects has its own consequences, for example, bullies at the bottom of the cylinder may not cause compression loss to the cold one, but may cause knocking and increased oil consumption on the warm engine, which is due to thermal expansion of the piston and changes in the gaps.
The charring of the valve, visible as a black funnel or melting of the edge of the plate, leads to loss of power and trimming of the motor. In this case, the camera clearly shows the loose adhesion of the valve to the seat. If you see cracks in the cylinder wall (often at the jumpers), then such an engine will not survive long - the crack will grow under the influence of temperature stresses.
The table below provides a transcript of the main visual signs and their probable causes:
| Visual sign | Probable cause | Effects of consequences | Elimination method |
|---|---|---|---|
| Deep vertical furrows | Catalyst destruction, detonation | Knocking, oil consumption, loss of compression | Cartridge or block replacement |
| Black loose-flap raid on the valves | Direct injection, short trips | Floating speed, loss of traction | Mechanical cleaning (sandjet) |
| Gone Hon (smooth walls) | Natural wear, bad oil. | Increased butter charcoal | Squandering or honing |
| Refrigeration of the piston | Poor mix, early ignition. | Piston burn, knock. | Replacement of the piston group |
It is important to understand that some defects can be treated without disassembling the engine, but most serious problems detected by the camera require intervention. mechanical So video defects are not just a way to satisfy curiosity, they're a powerful tool for making financial decisions.
⚠️ If the screen shows shiny metal shavings at the bottom of the cylinder or under the piston, further operation of the engine is strictly prohibited - this is a sign of active destruction of parts.
Frequent questions about cylinder diagnostics
Can I scratch the cylinder with an endoscope camera?
Yes, if you use a hard, low-quality probe or you act sloppy. Modern endoscopes have a smooth shell, but hitting abrasive (sand) on the end of the chamber when inserted can leave risks. Always clean the candle well before entering.
Do I need to turn candles on a cold or hot engine?
To assess the condition of the cylinders, it is better to inspect the engine with a slightly warmed up engine (cooled to 40-50 degrees) to see the real picture of the oil film, but it is safer and easier to twist the candles on a completely cold engine, so as not to get burned or break the thread.
Will the camera show the rings?
It's hard to see directly, because the rings are hidden in the grooves, but the indirect sign is the absence of oil film above the rings, the presence of a lot of sodium in the grooves of the piston, and the dry, coked cylinder walls above the ring zone.
What is the minimum diameter of the camera for the engine?
A standard candle well allows a chamber to pass up to 6-8 mm in diameter. However, for modern compact engines with narrow wells, it is better to use models with a diameter of 3.5-4 mm to have a range and not damage the candle thread or the camera itself.