outboard motor decoding: technologies, means and stages

Operating water machinery in trolling or idling mode often results in dense soot on the piston group, a process known as "coking" that reduces compression, increases fuel consumption, and can cause engine failure. Unlike car engines, outboard motors operate in specific temperature conditions, which requires a special approach to maintenance.

Timely boat-motoring It allows you to restore factory performance without expensive overhauls. If you notice a drop in thrust or hear a ringing when you open a throttle abruptly, you can't ignore these signals. The layers of coke on the bottom of the piston and in the grooves of the rings are a time bomb that can penetrate the cylinder wall at the most inopportune moment.

In this article, we will discuss mechanical and chemical cleaning methods, as well as the nuances of the use of soft and hard decoxers. Yamaha, Tohatsu or Honda For hundreds of hours, keeping you safe on the water.

Diagnosis of the state of the engine and symptoms of coking

Before action begins, you need to determine exactly if there is a problem. Owners often confuse the symptoms of fuel system pollution with the swelling in the combustion chamber. The main indicator here is compression and the nature of the exhaust. If the engine has become sluggish and reacts less to the gas handle, it is worth checking the condition of the candles and the cylinder-piston group.

Nagar is produced by the combustion of oil in two-stroke engines or the products of incomplete combustion in four-stroke ones. Especially critical is the condition of the rings: when they lose mobility due to coke, the cylinder leakage is disturbed, which leads to a gas break in the crankcase and a drop in power.

Pay attention to the following signs that require intervention:

• 🔥 The engine overheats even at normal temperature of off-shore water.
• 📉 A noticeable drop in compression in one or more cylinders when measured by a compressometer.
• 🌫 The appearance of gray or black smoke from the exhaust under load.
• 🔊 Knocking or ringing ("dieseling") when a sharp discharge or addition of gas.

Diagnosis is better to carry out comprehensively, using not only visual inspection, but also instrumental methods. Compression measurement If the difference between cylinders exceeds 10-15%, mechanical cleaning may already be inefficient and repairs will be required.

Chemicals for removal of sodium: the choice of the drug

The autochemical market offers many solutions, but not all of them are suitable for marine and river engines. Aggressive solvents can damage rubber seals or glands, which in outboard motors are often made of specific materials. The choice of means depends on the degree of pollution and type of engine.

There are three main classes of drugs: soft fuel additives act incrementally, cleaning the system during operation; hard fuels are poured directly into the cylinders and require the engine to stop for several hours; and the third type is professional ultrasonic bath chemistry, available in service centers.

⚠️ Note: Using acetone or pure Kalosha gasoline as a decoxer may cause rubber components of the fuel system to dry out. Use only specialized formulations such as: Shima, Lavr or Edial.

When choosing a drug, pay attention to its ability to dissolve solid fractions of soda, rather than just washing away sediments. For older engines with high mileage, it is better to use a phased cleaning, starting with sparing regimes. The sudden dissolution of large amounts of soda can lead to the fact that pieces of coke will clog the exhaust windows.

The important parameter is the evaporability of the product. The volatile components must effectively clean the top of the cylinder without leaving the film. Chemical decoking The rings are not yet completely geometry-free.

Preparation of the motor for the cleaning procedure

Well, preparation is 80 percent of the success of the whole operation, and before you start working, you have to warm the engine to the operating temperature, so that the heat gaps widen, so that the charcoal becomes more susceptible to chemical damage, and it's pointless to process the cold engine.

After heating up, the engine is jammed and removed spark plugs (in two strokes) or candles and coils (in four strokes). The candle holes are visually examined by means of a flashlight and endoscope, if any. The presence of oil in the cylinder before pouring hard chemistry is unacceptable.

The following actions are to be taken:

• 🛠 Disconnect the fuel hose and develop the residue of gasoline from the carburetor or ramp.
• 🧹 Clean the area around candle wells of dirt and sand so that they do not fall into the cylinders.
• 🔋 Charge the battery, as to scroll the starter will require a stable voltage.
• 🧤 Prepare a rag and a container for draining old liquid from cylinders.

Safety when working with paramount chemistry: the pairs of decoxers are toxic, so work should be done outdoors or in a well-ventilated room. The use of protective gloves and glasses is mandatory, as getting aggressive fluid on the skin or in the eyes can cause burns.

If you plan to use the "hard" decoking method, make sure you have a syringe with a tube for accurate dosing of the drug. Pouring the drug "on the eye" through the candle hole is uncomfortable and inefficient.

Technology of "hard" decoding: step-by-step instructions

This is the most effective method for highly contaminated engines, and the process is to create a high concentration of the active substance directly in the combustion chamber, and the engine does not start, and the chemistry works statically, softening and dissolving the deposits.

First, set the pistons to the middle position (about 50% stroke), which will provide access to the rings and walls of the cylinder from all sides. Pour 30-50 ml of decoxer into each cylinder (the exact amount is specified in the instructions for the drug). Leave the motor for 6-12 hours. Periodically, every 30-40 minutes, it is recommended to scroll the crankshaft with a starter for several revolutions, so that the liquid penetrates the rings.

Step-by-step algorithm of actions:

1. Warm up the engine to 40-50 degrees and turn off.
2. Unwrapped the spark plugs.
3. Close candle wells with rags so that dirt does not get inside during further manipulations.
4. Pour the product into cylinders and twist the candles (without tightening to the end to create pressure as the vapors expand) or leave open depending on the type of chemistry.
5. After exposure, remove the liquid with a syringe and blow the cylinders with compressed air.
6. Switch in old (or new) candles and start the engine.

The first start after the procedure will be accompanied by abundant white smoke and unpleasant odor, it burns out the residue of chemistry and dissolved soda, let the engine work at idle speeds for 5-10 minutes, then you can briefly raise the speed to medium. The decoking procedure It is considered complete when the exhaust becomes transparent.

⚠️ Warning: After the chemical drain, be sure to replace the oil in the gearbox and engine (for four-stroke engines), as part of the aggressive composition could get into the crankcase through the gaps of the rings.

Comparative table of cleaning methods

The choice of method depends on the condition of the engine and your financial capabilities, and the following is a comparison of the main approaches to removing the scorch.

Method	Efficiency	labour-intensiveness	Risk to the engine
Fuel supplementation	Low (prevention)	Minimum	Missing.
"Hard" chemistry	High.	Medium	Medium (aggressive chemistry)
Mechanical cleaning	Maximum	High (disassembly)	High (human factor)
Ultrasound	High.	High (needs service)	Minimum

Mechanical cleaning involves completely disassembling the engine, removing the cylinder heads and manually removing the soak with brushes and scrapers, which is the most reliable, but also the most expensive, method requiring qualifications. outboard motor decoupling The chemical method is the middle ground for most owners.

For two-stroke engines, it is important not to overdo the mechanical cleaning of the exhaust windows. Damage to the edges of the windows can disrupt gas exchange. In four-stroke engines, the risk of mechanical damage to the valves when cleaning the exhaust windows is also great.

Prevention of the formation of sodium and caring for the engine

The best decoking is not to have it, and to minimize the formation of sediment, you need to choose the right oil. For two-stroke engines, only use oils with the labeled oils. TC-W3Lower grade oils (TA, TB) form much more ash and soda.

Try to avoid long-term engine idling and low revs. In such modes, the temperature in the cylinder is not enough to completely burn the mixture, which leads to coking. Periodically let the engine gass at full throttle in safe mode.

It's also important to keep an eye on the fuel mix, so if you're cooking your own gasoline, mix the components thoroughly and don't store the mixture for more than a month, and the old gasoline loses its properties and contributes to the formation of resinous deposits.

Regular replacement of spark plugs also plays a role: Old candles with a large gap or soot give a weak spark, which worsens the quality of the mixture combustion. The optimal interval for replacement of candles for an intensively operated engine is 100 motor hours.

Frequently Asked Questions (FAQ)

Can I use the new engine to make the car?

The new mileage-free engine does not require a hard decoking, but adding a quality cleaner to the fuel (a mild method) after the first break-in (5-10 hours) will help remove the residue of the factory lubricant and preservatives, ensuring that the combustion chamber is clean from the first kilometers.

How many times a season do I need to do the procedure?

With active operation (more than 50 hours per season), preventive "soft" decoking is recommended 2-3 times per season. "Hard" method with cylinder soaking is used as necessary, usually every 2-3 years or when there are obvious symptoms of rings.

Will the engine be able to smoke blue smoke?

If blue smoke is caused by oil rings being deposited due to the soot, then decoking can help restore their mobility, but if the smoke is caused by wear of the cylinders or the destruction of the crankshaft glands, chemical cleaning will be powerless - mechanical repairs will be required.

Is it dangerous to hit the decoxer in the gearbox (for 2T engines)?

In two-stroke engines, some of the liquid inevitably enters the crank chamber. Modern decoxers are generally safe for bearings and glands in brief contact. However, after the procedure, it is recommended to replace the fuel filter and, if possible, blow the crankcase to eliminate the risk of corrosion in the future.