How to Prevent and Fix Engine Blowby

How to Prevent and Fix Engine Blowby
April 8, 2021

Every engine has some level of blowby, but what is blowby? Blowby is the leakage of any combustion gases or pressure into the engine’s crankcase. Most blowby occurs when exhaust gas enters the crankcase by going past the piston rings while other sources include turbochargers. Blowby that goes past the piston rings not only pressurizes the oil pan but also introduces combustion gases that contain unburned fuel, particulate plus create condensation due to the temperature differential of combustion gases and the crankcase. Engine oil mixed with blowby produces sludge and acids that attack engine parts. The unburned fuel dilutes the lubricity and viscosity of the engine oil, attacking engine bearings, the valve train, and cylinder walls.

Engine blowby can cause a plethora of problems. One of the most common is cracking piston rings and ruining HEUI fuel injectors in early Powerstroke engines. Ignoring this problem could not only cost your fuel injectors, but also it more than likely will foul your turbo, EGR Valves, and DPF. These are not cheap fixes either, you’re looking at being out thousands of dollars, and potentially dealing with the same problems in a few years. Overall you will notice a loss in engine performance and fuel economy. Air, fuel, and other contaminants will slip into the crankcase and cause all types of problems. This is because engine blowby causes gaps and cracks in the piston rings and by that time it’s often too late, you’ll be forced to replace piston rings, an expensive repair!

Tell-Tale Signs of Excessive Blowby

How do you know if you have excessive blowby? One of the tell-tale signs of excessive blowby is white smoke billowing from the block oil-fill or opening on a valve cover. To check this, set the oil-filler cap upside down on the tube or opening. If it immediately blows off, there definitely is too much crankcase pressure. Checking the engine’s compression by performing a leakdown test is a more detailed method of diagnosing the condition and determining the amount (percentage) of blow-by. The test is completed using a compressor and the specialized dual-gauge testing tool.

Piston from engine

How Do You Prevent and Fix Blowby

So is there anything you can do to prevent this from happening to your beloved truck? Actually yes, there is. It starts with using a high quality oil, like Hot Shot’s Secret Blue Diamond Engine Oil. By using a high quality oil you ensure your engine is running smoothly and reducing the friction that can cause engine blowby (caused by stiction). So using high quality oil is step 1, step 2 is actually cleaning out what causes engine blowby, stiction. We recommend adding Hot Shot’s Secret Stiction Eliminator every 3rd oil change to make sure your engine is free of stiction. Hot Shot’s Stiction Eliminator was specifically designed to safely clean your engine of stiction. By cleaning the stiction, the rings will move more freely, allowing for a tighter seal between the cylinder walls and the piston. That way you can avoid devastating engine blowby and the expensive manual cleaning of your pistons or even piston replacements.

No one wants to experience engine blowby and not one soul wants to have to pay for the damages engine blow by brings with it. The old saying “you get out what you put in” holds true for your diesel engine. It always pays off in the end to take care of your engine up front by using quality fluids and adding a little bit here and there to keep things clean and running smoothly.