Everything You Need To Know About Fixing Diesel Engine Leaks

The Tin Man isn’t the only thing that needs oil to thrive. Oil is an essential part of every vehicle, serving several purposes. Its primary function is to prevent the engine from seizing up and the various parts of a vehicle from rubbing against one another as they move. Without adequate oil, friction in the engine can rapidly wear down its components.

Depending on the root of the problem, diesel engine oil leaks range in severity. To assist you in recognizing and dealing with this issue, we have everything you need to know about fixing diesel engine leaks below.

Diesels Are Built Different

Every engine produces some amount of internal blow-by. Diesels, however, have a unique process for dealing with this blow-by. The term blow-by refers to an internal combustion engine’s exhaust gases that leak into the crankcase. Gasoline engines use blow-by to generate a vacuum, pushing the pressure into the intake.

For modern diesel engines, however, this feature is no longer available due to turbochargers. The intake pressure is already too high from the turbocharger for PCV to be effective. The turbocharger prevents the crankcase pressure from escaping because it drives air into the intake.

The diesel engine’s breather exhaust tube is next to the oil pan at the bottom. This is a common spot for oil leaks. The air intake hose is also here, where the exhaust fumes from the engine disperse into the atmosphere.

Oil Leak Levels

An oil leak is almost always grounds for immediate action, but all leaks differ. In fact, there are five levels of oil leaks. A leak is of the first magnitude if you only notice dry oil on the ground beneath your vehicle. It only leaks occasionally and in minimal amounts, so fixing the leak immediately might not be necessary.

In contrast, wet oil on the ground indicates a level two leak. If you notice this, it’s time to worry. A level three leak results in a wet spot at the leak point in the form of a droplet accumulating slowly but not falling. A level four leak occurs when said droplets begin to fall. And finally, oil flows freely with a level five leak.

Common Oil Leak Causes

As we mentioned, a small amount of oil dripping from the blower tubes isn’t too much of a concern. Often, folks see fluids dripping from this region and expect the worst. Fortunately, a minor trickle of oil is perfectly normal. However, anything more requires investigation. Below, we’ll review the most common causes of more significant oil leaks and how you can fix or prevent them.

Blown Gasket

Your vehicle’s cylinder blocks are home to several moving parts that keep your engine purring. The head gasket is the main component that protects these parts, providing a protective barrier for your engine’s pistons, cylinders, spark plugs, and camshafts.

The head gasket’s fundamental purpose is to seal the pressure from the cylinders and keep engine oil and coolant from leaking into the engine. With so much pressure on the head gasket, it eventually wears down or warps, losing its efficacy. Telltale signs your gasket is experiencing its final days include milky-colored oil, an overheating engine, bubbling in the radiator, and white smoke exhaust.

The Fix

Maintaining the engine coolant at the right amount and mixture according to the manufacturer’s suggestion is the best strategy to avoid head gasket failure in your vehicle.

Improper Oil Filter Replacement

There are several potential causes for a leaking filter because the oil in your car is under a lot of strain as it moves from one part to another. For example, inadequate tightening of the oil filter might result in oil leakage due to vibration. Likewise, if the previous filter’s gasket is stuck to the housing, oil leaks might also occur during the oil change process. When you install a new filter, you’ll have two gaskets instead of one, which might lend itself to another leak. Also, a new gasket might misalign during installation due to binding, crimping, or other mishaps.

Beyond proper gasket installation, the oil filter’s mouth has delicate metal threads that must remain intact and screwed in properly. Varying filters have visual similarities but function distinctly in different engines, so accidentally using the wrong filter could create problems. Oil can also leak through if the engine housing is compromised or if the mating surface between the filter and housing is filthy. Lastly, the filter might sustain physical damage due to collision and permit oil leaks.

The Fix

Being proactive during installation is the greatest approach to preventing filter-caused leaks. Before installing new filters, ensure the housing is tidy and devoid of dust and old gasket debris. Inspect the freshly installed filter for defects such as dents, broken threads, and cut or warped gaskets, and make sure you have the correct filter number. Apply a thin film of oil over the gasket to prevent it from sticking during installation. Then, hand-thread it onto the engine while being cautious not to overtighten the bolts. Always check the manufacturer’s specifications for the proper torque setting. Finally, make sure the oil is full.

Loose Oil Cap

The spherical cap on top of your engine is the oil filling cap. The oil fill hole remains sealed thanks to this feature. The cap prevents dirt, dust, and debris from entering the engine and lowering efficiency. The oil cap also plays a role in preventing oil leakage. The most obvious sign of a loose oil cap is smoke escaping from under your vehicle’s hood. Another sign is the smell of leaking oil.

The Fix

If you notice either of these warning signs, act swiftly before dirt and debris enter your engine. Also, you must always securely close the oil fill cap for optimal performance.

Bad Oil Pan or Plug

Leakage due to a bad oil pan has similar warning signs to a bad gasket, filter, or cap. However, when you inspect the oil pan, you might also notice a loose or detached oil drain plug. Fortunately, it’s hard to miss a poor drain plug when you inspect the oil pan. New oil accumulates around the plug and will likely leak down the plug’s side if it’s damaged.

The Fix

The fix for oil pan issues is a bit more complicated. You must jack your car high enough to access the pan, disconnect the cable to the battery’s negative terminal, and remove all the parts, including the gasket, bolts, and pan. After thoroughly cleaning the engine and the pan’s surfaces with a solvent, you can replace the gasket or damaged oil pan.

Now you’ve read everything you need to know about recognizing and fixing diesel engine leaks. Blessed Performance can provide the best aftermarket diesel truck parts to ensure you stay behind the wheel of a lean, mean trucking machine. Although we’re based in Gillette, WY, we ship parts nationwide!