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Diagnosing Diesel Blow By: Common Causes and Effective Fixes


If you own a diesel vehicle, you've probably heard the term "blow by," which refers to the process by which exhaust gases escape past the piston rings and into the crankcase. This can result in a variety of issues, including decreased engine performance, higher oil consumption, and even engine damage. In this blog, we'll look at some of the most prevalent causes of diesel blow by and offer solutions to help you diagnose and treat the problem.


Causes of Diesel Blow By


Worn Piston Rings

Piston rings play an important role in sealing the combustion chamber and preventing exhaust gases from entering the crankcase. However, piston rings can wear down over time, causing them to lose their sealing capacity. It is normal for blow by to occur when this occurs.


Worn Cylinder Walls

The cylinder walls are in charge of supporting the piston rings and maintaining adequate combustion chamber compression. If the cylinder walls wear or damage, it might cause compression loss and increased blow by.


Faulty PCV Valve

The positive crankcase ventilation (PCV) valve controls the amount of pressure in the crankcase. If the PCV valve becomes blocked or damaged, pressure in the crankcase can build up, resulting in blow by.


Dirty Air Filter

A clogged air filter can reduce airflow to the engine, causing it to work harder than necessary. This can result in higher crankcase pressure and blow by.


Effective Fixes for Diesel Blow By


Replace Worn Piston Rings

If your diesel blow by is caused by worn piston rings, the most effective solution is to replace them. This is a difficult repair that should be done only by a qualified mechanic.


Rebuild the Engine

If the cylinder walls are worn or damaged, the engine may need to be rebuilt to correct the blow by problem. This is a major operation that demands specific knowledge and equipment.


Replace the PCV Valve

Replacing a malfunctioning PCV valve is a very straightforward repair that most do-it-yourself mechanics can perform on their own. When installing the new valve, make sure to follow the manufacturer's instructions.


Replace the Air Filter

Replacing a filthy air filter is a quick maintenance that takes only a few minutes. Use the suitable filter for your car and install it according to the manufacturer's instructions.

Diesel blow by is a prevalent problem with a variety of causes. If you're suffering blow by, it's critical to appropriately diagnose the problem to avoid further engine damage. There are practical remedies available to help you get your vehicle back in top shape, whether you need to replace old piston rings, rebuild the engine, or simply replace a dirty air filter.

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