What Is Wet Stacking In Diesel Engines?

Wet Stacking is a phenomenon that occurs in diesel generator sets that are operated at low loads (less than 30% of rated capacity) for long periods of time. Because of the low running load, the engine does not achieve the optimal operating temperature for peak performance, resulting in unburned fuel and carbon deposits.

How do you prevent wet stacking?

Wet stacking is quite widespread in the field of diesel engines. If you don’t run your engine at recommended operating temperatures 100% of the time, you’re going to have some wet stacking. When diesel generators are not used at least 60% of the time, they run at suboptimal temperatures, which means the engine never achieves the temperature required to burn off the surplus fuel and carbon deposits, resulting in “wet stacking” in the exhaust system.

How Do I Know It’s Happening?

Black ooze surrounding the exhaust pipe or continuous black exhaust smoke are frequently the first signs of wet stacking. If you operate your generator below the recommended operating temperature, run it at less than 60% load, use the incorrect air-to-fuel ratio, leave it idle for lengthy periods of time, or run it with too much or too little fuel in the tank, you can presume it’s wet stacking.

How Can I Prevent It?

To avoid wet stacking, exercise your generator according to NFPA and manufacturer guidelines (at least once a week with at least a 60% load), run your engine at optimal temperatures, keep the fuel tank full, have a qualified technician maintain your generator at regular intervals, and make sure the internal temperature of your generator reaches manufacturer recommendations if you’re operating in cold conditions.

If you observe a buildup of gasoline and soot particles in your engine, the solution is sometimes as simple as running it at maximum power for a few hours to burn them off. Higher particle levels may need the use of a load bank to simulate a full load on your generator, as well as the use of a competent technician to complete the load banking procedure.

What Happens if I Don’t Address it?

Unburned fuel will begin to build up in your exhaust system if you do not address wet stacking at scheduled maintenance intervals. This can clog your injectors and reduce the performance of your generator. These gasoline deposits can also cause backpressure, degrade your engine’s surface, and reduce the overall system’s efficiency. These negative effects will dramatically reduce equipment life, resulting in higher repair expenses.

Wet stacking can also have an impact on the quality of your engine oil. The pistons do not meet the cylinder as they should since your engine is running at sub-optimal temperatures. Unburned fuel may leak into the oil pan, causing the oil to become diluted. This reduces the effectiveness of your oil to protect your engine and increases wear.

Wet stacking increases pollution, and most localities have laws prohibiting wet stacking-related smoke emissions. If the EPA discovers this, it can result in significant fines.

What causes diesel wet stacking?

A diesel engine, like other internal combustion engines, must have the exact air-to-fuel ratio and be able to maintain its designated operational temperature for a complete fuel burn to run at maximum efficiency. When a diesel engine is run at low speeds, it will not reach the proper operating temperature.

Unburned fuel is exhausted and noted as wetness in the exhaust system when the diesel engine runs below its designed operating temperature for lengthy periods of time, hence the term “wet stacking.”

What is wet stacking and how can it be prevented?

You can avoid wet stacking later on by carefully arranging your energy system with a sufficient load and capacity during the initial setup stage, so that you don’t regularly run a diesel engine below its suggested load. However, many businesses expect to expand, thus constant load banking is required to keep the engine running smoothly. Load banking allows us to run an engine at a higher-than-recommended capacity (often up to 80%) with predictable rates and stages for a set period of time without disrupting your business’s normal operations. During this time, we may keep a careful eye on your generator’s performance and clean away any unburned fuel that could lead to wet stacking.

Is wet stacking normal?

Wet stacking has a number of negative impacts on a diesel engine generator, and if left unchecked for a long time, it can lead to lower engine performance or permanent engine damage, necessitating a costly significant engine overhaul.

How long can a diesel engine run continuously?

Your car’s gasoline engine should last roughly 200,000 miles before it requires a major maintenance or you need to purchase a new vehicle. Diesel engines, on the other hand, may run for 1,000,000-1,500,000 miles without having any serious maintenance. In fact, a well-maintained diesel engine can last for 30 years or more on the road.

According to Capital Reman Exchange, there are three key factors for a diesel engine’s lifetime, endurance, and reliability:

A diesel engine is gear-driven in design. Gears, unlike other parts that might be broken or damaged, are easy to repair and never lose their timing. Gear-driven water and oil pumps are available on most diesel automobiles. Parts and components are less likely to fail as a result of this.

Diesel-powered vehicles are typically built with heavy-duty components that can withstand the vehicle’s power, resulting in less wear and tear on all parts of the engine.

Diesel engines are also fantastic since they are self-cooling, which means they have a far lower possibility of overheating. There are multiple sensors and thermostats in use, which means that if one fails, the engine will not overheat. A steady supply of coolant flows freely through the engine thanks to many piston-cooling nozzles.

Compression ignition is used by a diesel engine to use its fuel to power itself. This happens when diesel fuel and air are squeezed to the point that heat is generated, resulting in spontaneous combustion. This spontaneous combustion, according to Digital Trends, is significantly more favourable for a long-lasting engine.

Can a diesel engine get wet?

Wet stacking, if overlooked, can cause serious harm to your diesel engine over time. Unburned fuel will begin to accumulate in your engine, blocking injectors and reducing performance. Deposits can also cause backpressure and limit the performance of the turbo system of the engine. Worse, they’ll degrade engine surfaces over time, reducing the product’s lifespan.

Engine oil is also affected by wet stacking. Because the engine isn’t as hot, the pistons don’t expand as much as they should to contact the cylinder wall. Gases and unburned fuel enter the oil pan beneath the cylinder as a result, diluting the oil. This reduces the oil’s ability to protect your engine and causes it to wear out faster.

Higher pollution and emissions, reduced power, and increased maintenance are some of the other negative consequences.

Why is it called rolling coal?

You may have seen a pickup truck spewing massive clouds of black exhaust smoke on purpose at one point or another and wondered if it was allowed.

It’s referred to as “rolling coal,” and it is a real thing. Diesel truck owners who customize their vehicles so that they may belch smoke whenever the whim strikes are known as coal rollers. Often, this involves focusing on people and things they disagree with, such as Black Lives Matter protestors, bicyclists, and electric cars.

It’s not a new activity — truck drivers of a certain type have been rolling coal for several years — but it’s gotten a lot more attention recently.

Much of it is due to a viral TikTok video from October depicting an altercation inside a Texas hamburger business. A pickup truck blew smoke through an open front door, upsetting a group of youngsters dining after a football game.

A 16-year-old Texas kid driving a diesel pickup attacked a group of eight bicyclists on Sept. 25. He hit six of them as he approached to roll coal, sending four to the hospital. The motorist was charged with six counts of felony aggravated assault with a deadly weapon by the Waller County district attorney’s office on Nov. 8.

And there have been numerous instances of coal rollers targeting electric Teslas, presumably because they are offensive to coal rollers, but also because all Teslas are fitted with video cameras.

What is diesel slobber?

“When diesel engines are started cold, and more worse when the ambient temperature is chilly, “Fuel Slobber” occurs. This was a regular occurrence in the 1970s and 1980s, when most Cummins engines did not have variable timing. Because the Caterpillar 425-B had improved timing for cold idle engines, the fuel slobber wasn’t as terrible. The STC-444 Cummins engines also had enhanced idle timing, making them significantly cleaner. Many owner operators thought the fuel pouring from the flex line just behind the turbocharger was engine oil, however it was actually fuel and water combining with the soot in the exhaust system, which resembled oil. When the engine reached the proper operating temperature, which normally didn’t happen until the vehicle was driven, the problem would go away.

Diesel engines run cool due to their huge cooling systems and the large amount of air that passes through them while idling. A modern diesel engine produces roughly 67 percent nitrogen, 11 percent carbon dioxide, 11 percent water vapor, and 9 percent oxygen as a result of burning fuel. It makes up less than 1% of the total “all of the “bad” pollutants for which diesel exhaust has recently gained notoriety. On a cold start of a diesel engine, the water vapor in the exhaust system may be cold enough to condense into liquid water – notably on vehicles with vertical exhaust stacks. This liquid water can flow down the stack at numerous clamped joints, causing a mess on the chrome elbows, and possibly even leaking out of the flex pipe.

This is a good example “If the vehicle is put to work, the “fuel slobber” problem usually goes away in a few minutes, but if it is left idling, especially on a chilly day, the liquid water can be quite a nuisance. Most of us think that liquid water is bad for modern diesel particulate filters, especially if the engine is turned off before it is hot enough to transform the liquid into vapor and expel it from the filter. This is a good example “Slobber” can also leak through the connection joints of the exhaust manifold and flow down the side of the engine. Simply spritz the slobber with soap or penetrating oil and wipe it away with a towel if this happens (many penetrating oils are also very good cleaning solvents that will also help to keep the engine from rusting).

Blow-by can potentially cause damage to your truck’s engine and structure. The amount of blow-by produced by an engine increases with the horsepower and the amount of time it is operated. Blow-by is just compression passing through the piston rings, and it occurs in all engines. The Oil Trap, which attaches to the bottom of the blow-by tube, is a great way to trap the oil residue that can be found in the blow-by gases. Every 10,000 miles, this Oil Trap will catch around half a cup of oil, which is better kept in a container than smeared all over the underneath of your truck.

Drive a motorcycle down the strip in Las Vegas while it’s raining to see the effects of blow-by on the pavement. When you step into the road, it will try to pull you out from under you. That is something I can tell you from personal experience, because holding up an Ultra Classic with a passenger in the back seat is difficult! Many mechanics will tell you that if you see blow-by coming out of the tube, the engine is worn out, but this is not true; oil consumption, not blow-by, is the way to tell if an engine is worn out. When one gallon of oil is spent every 2,500 miles, the engine is considered worn out and must be rebuilt, but not until then.

Let’s talk about the small 3/8-inch blow-by tube positioned on top of just one of the three valve covers, which I haven’t mentioned in a long time, but now that the Big Cam Cummins engines are regaining popularity, let’s talk about it. This may have sufficed when the NTC350 and 400 horsepower engines were popular, but not any longer, especially since we began raising the power to 700 and 800 horsepower. With the rise in horsepower came an increase in blow-by, so we began inserting a breather tube on each of the three valve covers, which fixed the problem.

Blow-by gases must evacuate the engine, and if the blow-by tube is insufficiently large, they will attempt to escape up the turbocharger drain tube. The oil pouring out of the turbocharger’s bearing housing is whipped and foamy, and it drains by gravity. Keep in mind that all turbocharger drain tubes must be less than 30 degrees from vertical, otherwise the oil will be driven past the compressor and turbine wheel seals.

Consider this: if blow-by is attempting to escape through the turbo drain tube, the turbo oil will be driven out of the turbo seals rather than draining down the tube. As a result of the limitation in the blow-by tube, many turbochargers are replaced. The filter prior to the blow-by tube on newer ISX Cummins engines must be updated. Never attach a heater hose on the bottom of the blow-by tube, since the hot gases will soften the rubber, and the wind under the vehicle will drive the hose horizontal, choking off the blow-by gases. Now, a turbocharger is being blamed for oil leaks when it’s simply that hose you place on the blow-by tube.

I write these articles to get you thinking; I want you to be aware of what’s going on under the hood of your truck while you cruise down the highway, especially when ascending a mountain. Stay watch for additional information about this next month as we prepare to start doing a bi-monthly video on YouTube and on our website.

How do pilot injections reduce combustion noise?

With the widespread usage of common-rail fuel injection systems in diesel engines, the pilot injection approach has received more attention for reducing pollutants emissions and combustion noise. Pilot injection tactics result in a leaner and more homogeneous mixture in the combustion process, which partially fulfills Premixed Charge Compression Ignition (PCCI). As a result, partial PCCI can be applied to the combustion process of diesel engines using a pilot injection technique (PPCI). Pilot injection raises the in-cylinder temperature before main injection, which minimizes the ignition delay of the main spray and, as a result, the combustion noise, allowing the PPCI combustion model to be extended to high-load operation. However, because the mechanism of pilot injection impacts on combustion noise is not thoroughly known, it is difficult to determine the lower combustion noise among various pilot injection settings, making correct selection of pilot injection parameters problematic. Experiments were carried out on a single-cylinder DI-diesel engine with pilot and main injection under high load operating circumstances for this research. To investigate the impacts of pilot injection on combustion noise, a unique approach of synthetic in-cylinder pressure levels (CPLs) in various frequency ranges was developed. The findings show that the high frequency combustion noise is mostly influenced by pilot spray combustion, and that the later the pilot injection timing, the higher the combustion noise. When the time between pilot and main injection is short, increasing the pilot injection quantity increases the high-frequency combustion noise. In the meantime, because the pilot injection quantity has increased, the main injection quantity has decreased, resulting in lesser combustion noise in the middle frequency band.

What is wet stacking on a tractor?

Unburned gasoline travels through the exhaust system, causing wet stacking in diesel engines. The term “stacking” is derived from the word “stack,” which refers to an exhaust pipe or chimney stack. As a result, the greasy exhaust pipe is referred to as a “wet stack.”

This syndrome can be caused by a variety of factors. Idling the engine for long periods of time is the most prevalent reason, as it does not generate enough heat in the cylinder for a full burn. “Idling” refers to a machine that is running at full speed but with very little load applied. Excessive fuelling is another issue. This could be due to faulty or leaky injectors, excessively high fuel settings, or overfueling for the given rpms. Running the engine in cold weather or for other reasons that prevent it from reaching the proper operating temperature might result in a buildup of fuel due to incomplete combustion, resulting in ‘wet stacking.’ It’s usually because the diesel engine is only producing a small proportion of its rated output in diesel generators. A diesel engine should not be operated at less than 60% of its rated power output for efficient combustion.

The presence of a black ooze around the exhaust manifold, pipework, and turbocharger, if fitted, indicates wet stacking. It’s sometimes mistaken for lubricating oil, but it’s actually the “heavy ends” of diesel fuel that don’t burn when the combustion temperature is too low. The heavier, oilier components of diesel fuel have more energy stored in them than, example, gasoline, but diesel requires a sufficient load on the engine to sustain combustion temperature high enough to use it. Due to gasoline accumulation, one can often hear a minor miss in the engine. When the engine is first put under load after long periods of idling and wet stacking, it may emit black exhaust when the surplus gasoline is burned off. When the stack is under constant load, continuous black exhaust indicates that some of the fuel is not being burned. Furthermore, due to the low temperature in the engine, wet stacking can result in a build-up of diesel fuel in the engine that does not combust. As a result, the fuel economy suffers. This fuel leaks into the cylinders, causing the engine oil to become diluted. This diluted oil, if not changed on a regular basis, can cause increased cylinder wear and premature engine failure. Wet stacking can cause stack fires in extreme circumstances.