A Few Things You Need to Know About Diesel Engine Blow-By

What is blow-by in a diesel engine? What causes it?

When the seals between the engine piston and cylinder wall are damaged, the fuel-air mixture leaks into the crankcase. This phenomenon is what we call blow-by in a diesel engine. There are many reasons for this problem; some are listed below:

Cylinder wall wear

Daily use of a diesel engine leads to cylinder wall wear. Due to the constant scraping of the piston rings, the cylinder bore increases over time. This results in a gap between the cylinder and the piston. This gap widens, allowing compressed gas to freely bypass the piston.

Piston wear

Over time, pistons wear down and shrink slightly. Because aluminum is a soft metal, grit that accumulates in the combustion chamber eventually forms grooves on the piston. As a result, the compressed fuel-air mixture seeps into these grooves and leaks into the crankcase.

Rings are worn

According to extensive research on piston rings conducted by researchers at Helsinki University of Technology, a common cause of engine blow-by is worn piston rings. As mentioned earlier, due to the back-and-forth friction of the piston rings, the cylinder walls gradually wear down the piston rings, reducing their sealing performance. Therefore, blow-by occurs in front of the piston rings, allowing gas to bypass them and leak. With wear on the sidewalls of the piston rings, gas also leaks from the back of the piston rings.

Reduce Engine Blow-Away Gases with Proper Oil Treatment

Using suitable oil additives can increase the oil's thickness, fill gaps, and reduce blow-away gases. Furthermore, this helps maintain dry, worn oil seals, preventing leaks from the valve cover and oil pan. Even if you have limited experience maintaining a car engine, you can add oil additives to your vehicle's engine. Here are the specific steps:

Open the hood. Locate the engine filler cap and unscrew it. To remove the cap, rotate it counter-clockwise. In some cases, you can pull it out or gently twist it. Take the smaller end of the funnel and insert it into the oil filler hose.

Pour the prescribed amount of oil treatment additive into the funnel. Ensure the funnel is clean and free of debris or other foreign objects.

Remove the funnel after the last drop of oil additive has been injected into the engine. When removing the funnel, be sure to cover the opening with a cloth to prevent any dripping additive from onto the engine.

Replace the oil filler cap in its original position.

Make sure the vehicle hood is closed.

Get into the vehicle and start the engine. Allow the engine to warm up to normal operating temperature. This helps the oil additive mix thoroughly with the engine oil.