How Much Blowby is Normal Cummins

A small amount of blowby is normal for a cummins engine. Blowby is the circulation of combustion gases and unburned fuel into the engine’s crankcase.

Cummins engines are reliable and efficient, but like any engine, they may experience blowby. Blowby can be caused by worn out piston rings, damaged seals or cylinder walls, or other issues. A small amount of blowby is usually considered normal, but if the blowby is excessive, it may indicate a more significant problem. It is important to properly maintain and inspect your cummins engine to ensure it operates at optimal performance levels. If you detect excessive blowby, it is recommended to consult a certified mechanic or cummins dealer to diagnose and resolve the issue. By detecting and addressing any issues early on, you can prolong the life of your cummins engine and ensure reliable performance.

How Much Blowby is Normal Cummins


Blow by …. when is it too much _ 12 valve Cummins _ Dodge first gen

Frequently Asked Questions Of How Much Blowby Is Normal Cummins

How Does Blowby Affect Cummins Engines?

Blowby can result in lost power, increased oil consumption, and higher emissions levels. It can also cause deposits to build upon engine parts.

Is It Normal For Cummins Engines To Have Blowby?

Some blowby is normal in all engines, including cummins engines. However, excessive blowby can indicate a problem with the engine or its components.

What Causes Excessive Blowby In Cummins Engines?

Excessive blowby can be caused by worn or damaged piston rings, worn cylinder walls, or a clogged crankcase ventilation system. These issues can lead to increased blowby and decreased engine performance.


In essence, blowby is a common issue in cummins engines. While some level of blowby is normal in an engine, excessive blowby can lead to possible engine problems. The signs of increased blowby include oil leaking, decreased engine performance, the presence of foamy or milky oil, and black smoke from the exhaust pipe.

There are different approaches to resolving blowby issues. Some opt for a simple approach of changing the oil or engine treatment, while others may have to replace parts or rebuild the engine. Whatever the solution, it is important to keep the engine well maintained and regularly checked to ensure that performance is not hampered.

By adhering to these methods, you can detect and fix blowby issues before they become severe and costly to repair. So, if you want to avoid expensive engine repairs or even replacement, pay close attention to the signs that point towards excessive blowby and follow the necessary steps to maintain your cummins engine.

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