Removing lacquer deposits in the engine: a complete guide to decoking

Modern internal combustion engines, whether reliable diesel units or boosted gasoline engines, inevitably face pollution problems during operation. polishThese are the hard, resinous oxidation products of oil and unburned fuel that act as an abrasive and an insulator, gradually disabling even the most advanced machinery.

Ignoring the symptoms of coking can lead to catastrophic consequences, such as cylinder bullying or piston ring breaks. Unlike conventional soda, which is often soft and easily removed, lacquer film has high adhesion and heat resistance, which is why standard oil replacement or short-term washing "five-minute" often proves powerless against long-standing deposits, requiring a deeper and more competent approach to maintenance.

In this article, we will examine in detail the physics of lacquer plaque formation, consider proven methods for removing it and evaluate the effectiveness of various chemical compounds. combustion-boxThis will not only help you to extend the life of the engine, but also to avoid expensive overhauls. Competent maintenance is not just a replacement for consumables, it is a set of measures to preserve the geometry and mobility of all CPG nodes.

The nature of the formation of lacquer deposits and their impact on the CPG

The process of varnish formation begins with the thermal decomposition of motor oil. At high temperatures, especially in the area of piston rings, the light fractions of the oil evaporate and the heavy fractions oxidize to form viscous resins. Over time, under the influence of cyclic heating and pressure, these resins polymerize, turning into a solid, vitreous substance. The critical temperature of the beginning of active lacquer formation for most mineral and semi-synthetic oils is 220-240 ° C, but modern synthetic base oils are able to withstand heating up to 280 ° C without losing properties.

The main danger is that the varnish blocks the mobility of the piston rings. Compression rings stop snugly adjoining the cylinder walls, leading to a compression drop and the crankcase gases break into the combustion chamber. Oil rings that have lost mobility stop effectively removing oil from the cylinder walls, which leads to a smack of lubricant. There is a vicious circle: more oil burns, more varnish is formed.

In addition, lacquer deposits have low thermal conductivity; a varnished piston is worse at discharging coolant heat, which can cause local overheating and even burnout of the bottom of the piston or valves. Direct injection and turbocharging engines, where the temperature of the CPG units is much tighter than that of distributed injection atmospheric motors, are particularly prone to this problem.

It is important to understand that the rate of sediment formation is directly dependent on fuel quality and oil change intervals. Using fuels high in sulfur or aromatic hydrocarbons accelerates the aging process of oil. Also, frequent trips over short distances when the engine does not have time to reach operating temperature, and condensate accumulates in the crankcase, emulsifying oil and accelerating its oxidation.

Diagnosis of coking: symptoms and methods of verification

Before you start aggressive cleaning methods, you need to make sure there's a problem. There are a number of indirect signs that can indicate rings and lacquer deposits, first of all, it's increased oil consumption for carbon monoxide. If your car starts eating oil for a thousand liters of oil for a thousand kilometers, although it has not been driven before, it's an alarm bell.

The second major symptom is loss of dynamics and floating idling speeds: coked valves or cylinder leakage due to fixed rings lead to unstable engine operation, can also be difficult to start, especially for cold, and increase the pressure of crankcase gases, which often expels oil through the oil seals and ventilation.

For accurate diagnosis, it is recommended to carry out a number of procedures:

• 🔍 Compression measurement - shows the ability of cylinders to maintain pressure; low values may indicate the occurrence of rings.
• 💧 Oil test (pressure) Adding oil to the cylinder when measuring compression; if the compression has increased, then the rings are not held.
• 🔭 Endoscopy Visual inspection of cylinders and pistons through the candle hole with the camera, allowing you to see the color and structure of the plaque.
• 📉 Exhaust analysis - elevated hydrocarbon content (CH) indicates incomplete combustion of the mixture due to problems with CNG.

The most informative method to date is endoscopy, which not only shows the presence of soda on the bottom of the piston, but also assesses the condition of the hon pattern and the presence of bullies. If you see mirror shine on the walls (leasing), this suggests that the wear process has already gone far, and chemical cleaning can be ineffective or even dangerous.

Chemicals for removing varnish: review and comparison

The autochemistry market offers many anti-deposition drugs, but their effectiveness varies dramatically: conventionally, all of them can be divided into soft oil additives and hard-cooking, poured directly into the cylinders. The first work for the future, gradually dissolving the deposits, the second is designed for shock therapy in case of already encountered problems.

Soft cleaners, added to the oil 200 to 500 kilometers before being replaced, contain solvent and dispersant packages that are effective against fresh soda and can prevent further varnishing, but they are often powerless against old coke turned into a polymer, and their job is to keep it clean, not to treat the severe forms of coking.

Aggressive compositions, such as Shumacher FX350, Kangaroo Profoam 2000 or specialized lines from Lavr and Hi-GearThey contain powerful solvents (often based on solvents or acetone) and surfactants, which can soften and dissolve even hard lacquer films, but their use requires strict adherence to technology, as they can damage rubber seals and omentation during prolonged contact.

⚠️ Attention: The use of aggressive mileage decoding on engines can cause softened soda to clog the oil pump or filter, causing oil starvation. Be sure to assess the condition of the engine before the procedure.

When choosing a product, it is important to pay attention to its composition and purpose. Some drugs are designed only for gasoline engines, others are versatile. For example, chlorine-containing solvents are great for varnish, but require careful neutralization and removal, since their residues in the oil lead to corrosion of parts.

Technology of engine decoding yourself

The procedure for removing lacquer deposits by pouring into cylinders (hardcore decoking) requires preparation and compliance with safety precautions. To work, you will need: a candle key, a syringe with a tube, a decoking tool, fresh engine oil and a new oil filter. The engine must be warmed to the operating temperature (about 90 ° C) to ensure the maximum reaction of chemistry with deposits.

First, we unscrew all the spark plugs (or nozzles, depending on the design, but the candles are preferred for access), turn the crankshaft with a starter to put the pistons in approximately the middle position, then pour 30-50 ml of decoxting liquid into each cylinder, and it is important not to pour the liquid into the exhaust manifold in large quantities, which can damage the catalyst.

Then we screw the candles back in (without tightening to create pressure as the vapor expands) or just cover the wells with rags. We leave the engine to sour for 1 hour to 12 hours, depending on the manufacturer's recommendations and the degree of contamination. In the process, you can turn the crankshaft several times so that the liquid penetrates all the nooks of the rings.

After aging, you have to remove the remaining liquid from the cylinders, and to do this, we twist the candles and actively twist the starter for 10-15 seconds, pre-close the candle holes with a cloth to throw the residue of chemistry and dirt through the holes, only then you can twist the candles, start the engine and warm it up until the fan is turned off, then immediately change the oil and filter.

Comparative analysis of CPG cleaning methods

The choice of cleaning method depends on the state of the engine and your goals. Mechanical disassembly gives 100% results, but it requires a huge amount of time and money. Chemical flushing is less efficient, but it is accessible to everyone. Let's look at the main differences in the table.

As you can see from the table, cylinder-coking is the middle ground for mileage engines that don't need major repairs yet, but already have problems with oil charcoal. The mechanical method is inevitable if the rings are already dead or there are bullies that the chemistry won't take away.

Also worth mentioning is the drip-tray method, which is fed to a working engine through a vacuum hose or candle hole, which allows the chemistry to work with the engine running, constantly updated, and is considered more gentle and effective for cleaning valves and combustion chambers than static soaking.

Prevention of re-formation of nagara

After successful removal of lacquer deposits, it is important to consolidate the result and prevent their recurrence. The key factor here is the quality of the motor oil. Use products with a high alkaline number and a modern pack of detergent additives. Synthetic oils on a PAO or ester basis oxidize more slowly and form less high-temperature deposits.

Reducing the intervals of oil change is another effective method: If a manufacturer recommends changing the oil once every 15,000 km, and you operate a car in the city, reduce this interval to 7-8 thousand kilometers. In conditions of traffic jams and frequent starts, oil ages much faster, and its detergent properties are depleted long before the deadline.

It is also important to monitor the temperature of the engine: avoid overheating and prolonged operation at low speeds under load. Periodically, once in several thousand kilometers, it is useful to "burn" the engine, driving along the highway at high speeds (in the allowed range), This helps to self-clean candles, valves and pistons from fresh soak.

Keep in mind the crankcase gas ventilation (PCV) system. If the PCV valve is jammed, the crankcase pressure increases, and the oil enters the intake manifold more actively, where it burns and forms soda. Regular inspection and cleaning of the ventilation valve is a simple but important procedure.

Frequently Asked Questions (FAQ)