5.9 Cummins Excessive Crankcase Pressure/White Smoke
Issues With 5.9L Cummins Excessive Crankcase Pressure
Crankcase pressure happens when combustion gases, called blow-by, escape past the piston rings and buildup in the engine’s crankcase. A little blow-by is normal in diesel engines like the 5.9L Cummins, but too much can cause serious issues, including oil leaks and engine damage. It’s essential to identify the causes of excessive crankcase pressure and fix them promptly to keep your engine running smoothly and avoid more expensive repairs later.
What Causes Excessive Crankcase Pressure in a 5.9L Cummins Engine?
Several circumstances could lead to excessive crankcase pressure. Here are some of the most common.
Stuck Piston Rings
If you notice excessive white smoke from the oil fill cap, reduced power or rough idle, it could be due to stuck piston rings. This issue occurs when rings stick in the cylinder bore, forcing combustion gases — such as fuel, air and moisture — past the piston rings into the crankcase. To fix this issue, use a product like Hot Shot’s Stiction Eliminator that removes burnt oil and carbon deposits to free the piston rings.
Worn Piston Rings
Low compression, misfire in one or more cylinders, excessive blow-by, and oil consumption are all symptoms of worn piston rings. When piston rings no longer seal properly due to wear, significant combustion pressure escapes into the crankcase. Conduct a compression test to identify cylinders with low compression and replace worn piston rings.
Excessive Moisture or Contaminants in the Crankcase
If your 5.9L Cummins engine shows signs of excessive crankcase vapor, white smoke, milky oil or sludge buildup, this issue could be caused by moisture contamination from short trips in cold weather or poor crankcase ventilation. Regular oil changes are essential to remove contaminants. Also, check and repair the crankcase ventilation system to ensure proper airflow.
Faulty Crankcase Ventilation System
A buildup of pressure in the crankcase, oil leaks and excessive white smoke from the oil fill cap are signs of a faulty crankcase ventilation system. This problem could be due to a clogged or malfunctioning crankcase ventilation valve (CCV), which restricts the release of crankcase gases. To fix this issue, clean or replace the CCV.
Cylinder Scoring or Damage
If you notice significant blow-by, low compression and engine knocking, you may be dealing with cylinder scoring or damage. This problem is usually due to cylinder wall damage caused by overheating, poor lubrication or contamination. Inspect the cylinder walls using a borescope and resurface or replace the damaged cylinders.
How to Diagnose Excessive Crankcase Pressure in a 5.9L Cummins
Diagnosing Cummins 5.9L engines’ excessive crankcase pressure is crucial for maintaining engine health and performance. There are several ways to identify the underlying issue, including:
- Oil filler cap test: Place the oil filler cap upside down on the filler hole while the engine is running. If the cap blows off or moves significantly, it indicates excessive crankcase pressure. In this case, you’ll need further diagnostics to test the piston rings, CCV system and cylinder walls.
- Compression test: Use a compression gauge to measure each cylinder’s compression and identify problematic ones. Low compression in one or more cylinders indicates worn-out piston rings or cylinder damage.
- Inspect the crankcase ventilation system: Check for blockages or damage to the crankcase ventilation valve or hoses. Clean or replace any blocked or faulty components to restore proper ventilation.
- Visual inspection for leaks or damage: Look for oil leaks around seals or gaskets, which indicate excessive crankcase pressure. Replace damaged seals or gaskets once you’ve resolved the underlying pressure issue.
How Can You Prevent Excessive Crankcase Pressure?
Boost your 5.9L Cummins engine’s performance and prevent excessive crankcase pressure with our third-party tested products.
Hot Shot’s Secret Diesel Extreme
Hot Shot’s Secret Diesel Extreme is designed to optimize your diesel engine’s performance. It removes carbon buildup from injectors and boosts the efficiency of your entire fuel system. Minimizing contaminants entering the crankcase keeps your engine running cleaner and reduces wear over time. This powerful formula also improves fuel combustion, leading to smoother engine operation and more power.
Regular use of Diesel Extreme reduces blow-by, helping extend the life of your engine. Add Diesel Extreme every 6000 miles and use Everyday Diesel Treatment with every fill-up to keep your fuel system performing at its best. Both products have a cetane booster to enhance diesel combustion efficiency, minimizing soot buildup that can compromise the performance of piston rings.
Hot Shot’s Secret Green Diamond Engine Oil
Hot Shot’s Secret Green Diamond engine oil is a high-performance synthetic oil that extends the life of your turbo, injectors and engine. Green Diamond engine oils are infused with our FR3 Nano Technology® for the best possible protection of your engine. These oils are designed to handle high combustion pressures and provide exceptional support for engine components, reducing wear on piston rings and cylinder walls. Minimizing friction helps maintain optimal compression, which can reduce blow-by and excessive crankcase pressure.
Use Green Diamond engine oil during regular oil changes to enhance performance and protect your engine.
Support Your Engine’s Health With Hot Shot’s Secret
We develop effective formulas to help you keep your engine running smoothly. If you’re maintaining your 5.9L Cummins to resolve excess crankcase pressure, purchase Diesel Extreme or Green Diamond engine oil to make the most of your maintenance.
