How To Measure Crankcase Pressure On A Diesel Engine?

With more over 8,000 hours on our primary engine, increased oil leaks are to be expected. However, it had leaked almost nothing until lately, and the switch to leaking more occurred swiftly, so we decided to investigate further. Loose fasteners, worn/old gaskets and seals, and excessive crankcase pressure can all lead to oil seepage. Crankcase pressures of up to two inches of water column are allowed, according to the Deere specification.

A manometer is the instrument used to measure the crankcase pressure. You can make one out of a U-tube that has been calibrated in inches and is partially filled with water. We decided to get an electronic manometer because they are quite inexpensive and simple to operate. I used manometers to calibrate multi-carburetor systems on exotic automobiles in a previous profession as a mechanic, so I’m familiar with them. We bought a TK and put Dirona’s name on it.

Because our engine lacks a dipstick tube and instead uses a combined oil fill cap and dipstick tube, gauging the crankcase pressure is difficult. As a result, adapting the 1/4 hose from the manometer to seal onto the engine in order to read the crankcase pressure was not immediately clear.

We ended up utilizing a short stretch of silicone hose that seals inside the oil fill port and a wood-through hull plug with the manometer adaptor put into the hose at the end. It wasn’t particularly attractive, but it did the job, and that’s all that mattered. The results were intriguing: the water pressure was a consistent 2.3 to 2.4 inches at all engine rpm. Something wasn’t right because this was above the Deere specification of up to two inches.

Excessive pressure in a crankcase can occur for three reasons: 1) a clogged or malfunctioning exhaust gas recirculation system (causing pressure to build), 2) leaking turbocharger oil seals (letting compressed air into the turbo lubricating oil drain back), or 3) excessive leakage through the engine piston rings (essentially a worn out engine).

We started with option one because it is the cheapest and easiest to handle. We replaced the Racor Airsep filter (oil/vapor separator) and investigated the exhaust gas recirculation system for any additional potential blockages.

This is fantastic news. The crankcase pressure dropped to a safe level, indicating that the engine is still in good shape. At idle, we measured 0.15, 0.00 at 1,500 RPM, and -0.20 at 2,000 RPM. Oil seepage has been resolved, and the engine appears to be in good working order, with good turbo seals and piston rings that aren’t even showing signs of wear. It’s an excellent engine.

Should the Airsep filter be replaced on a regular basis? There is no Deere-recommended replacement timeframe that I am aware of, and if there is, I haven’t been able to locate it. I’m not sure what era we’d utilize for replacement. We’ll probably just put an entry to our maintenance diary every six months to monitor crankcase pressure and replace the filter if the pressure rises again. So the test is clean and quick, we’ve chopped down the tubing we used to produce the initial pressure measurement into a compact, easily accessible package.

What is a typical diesel engine crankcase pressure?

In most diesel engines, the maximum allowed crankcase pressure is between 1.0 and 4.0 H2O. For diesel engines, contaminated crankcase emissions can be a major issue.

What is the usual crankcase pressure?

What is the definition of crankcase pressure? Simply said, it’s the pressure in your engine’s crankcase that is higher than atmospheric (or positive pressure). You might measure the amount of crankcase pressure created in your engine by placing a pressure sensor or a pressure gauge on the crankcase. We installed a pressure sensor to our dyno to detect crankcase pressure on each car we dyno test, thanks to David Buschur’s suggestion. When the engine is in normal working condition, we commonly measure peak crankcase pressures on the range of 2.5 to 6.0 psi on engines employing the factory specified crankcase ventilation system (a PCV or “positive crankcase ventilation system”).

In a diesel engine, what generates excessive crankcase pressure?

Every engine has some level of blowby, but the issue is magnified when it comes to huge diesels. Excessive blowby is the result of a big cylinder bore, high cylinder pressure from turbocharging, long hours of operation, and poor maintenance.

Blowby is defined as the leakage of any combustion gases, air, or pressure into the engine’s crankcase. On a large diesel, around 60% of the blowby passes through the piston rings and into the crankcase. When the pressure differential in the cylinder bore is greater than the pressure in the oil pan, this occurs. As a result, blowby is greatest during the expansion (power) stroke of the engine and lowest during the compression stroke.

When the crankcase pressure is too high, what happens?

Venting a conventional V-8 engine isn’t difficult. Usually, all that’s required is a breather atop each valve cover. Of course, replacing one with a PCV valve to introduce some vacuum into the system and redistribute the unburned hydrocarbons back into the engine via the carburetor or throttle body results in a cleaner and more environmentally friendly alternative. Supercharged applications, on the other hand, can be finicky. When employing a standard push-in style breather, increased pressure in the crankcase might produce blow-by, coating that trick engine compartment in a fine mist of fuel-oil. Adding a PCV valve is an excellent idea until the engine is boosted, at which point the internal check valve is forced shut, leaving the valve useless. Instead of pulling new air into the breather and using the PCV valve to relieve the crankcase pressure, the internal pressure is vented out the breather, potentially leading in another greasy blow-by incident. When the engine is under load or at high rpm, pressure builds up quickly and needs to be alleviated the most.

What is the method for calculating crankcase blowby?

Contrary to popular belief, an engine has more blowby at idle than at higher rpms, according to one blowby flow meter manufacturer. The rings actually seal better as the speed increases, and blowby decreases.

What is the normal amount of blowby? By multiplying an engine’s maximum horsepower output by 50, you may get a rough estimate of how much blowby to expect. With normal piston rings and ring end gap tolerances, a street performance engine with roughly 500 horsepower will typically have about 10 cfm of blowby. Higher-performance engines with tighter tolerances, as well as those with gapless piston rings, are likely to have less blowby. For example, a NASCAR motor with 800 to 900 horsepower might only have 5 cfm of blowby.

On a 6.0 Powerstroke, how do you put a Blowby to the test?

Whether you like it or not, the 6.0L Ford Power Stroke, as one of the ‘big three’ diesel engines on the road, has had a significant impact on the market in its four years of production. The Ford-based 6.0 was developed as a step above the 7.3L in performance and fuel economy, with increased emissions characteristics to meet tighter federal rules. It was adapted from the International’s VT365.

Unfortunately, the motor design had problems that earned it the reputation of being a lemon in some circles. The Power Stroke’s reliability and reputation suffered as a result of computer faults and related injector concerns. However, the motor did have certain advantages, and many people noticed improvements in throttle response and overall performance over the previous 7.3L. The smaller engine was equipped with a new HUEI injection system as well as an improved variable geometry turbocharger (VGT), and the savings at the pump were evident.

And, while the motor design has received mixed reviews, a few common problems have continued to plague their owners. Owners, on the other hand, can shoulder responsibility, and those who keep up with maintenance see the 6.0L Power Stroke deliver strong and consistent results. We’ll go over a few of the most pressing challenges, along with some suggestions for how to address them:


White exhaust smoke in the 6.0L Power Stroke could be caused by a number of issues, including injector clogging and/or a failing EGR cooler.

Problem: If the owner detects white smoke, especially at start-up, it could be unburned fuel in the chamber caused by a stiction-clogged injector. The unburned gasoline generates the white smoke associated with cold starts until the engine’s combustion temperatures warm up.

Solution: Use a full dose of Stiction Eliminator to clean your fuel injectors and assist eliminate smoke buildup during normal operations and cold starts. Furthermore, poor gasoline quality may result in condensation in the fuel without the owner’s knowledge. Diesel Extreme helps to clear away condensation and enhance cetane if the “water in fuel” light is on, or even if there is a suspicion of water in the fuel. Always change your fuel filter if there is any water in the fuel.

Problem: A failed EGR cooler can produce white smoke that is actually steam, signaling a coolant leak into the exhaust system. The faulty EGR cooler, which is the initial EGR system in the Ford diesel, can be replaced with an upgraded aftermarket cooler, which is available as an improved substitute over the factory one.

Differentiate between coolant and fuel as follows: It’s coolant if the exhaust smells slightly sweet. It’s unburned fuel if the exhaust smells like bug spray.

Rough-running operation of the 6.0L Power Stroke could be caused by a number of issues, including injector stiction and/or injector mechanical failure.

There is a possible stiction build-up in the injectors if the vehicle runs rough when starting cold but clears while the engine is running warm, and/or if the truck runs rough during idle.

Solution: Pour a dose of Stiction Eliminator into your gummed-up injectors to clean them out, which will improve both normal operations and cold starts. Add in Diesel Extreme at the fuel pump for a double-punch to the system, cleaning out the entire fuel system.

Problem: If the truck is always running rough, a severe case of stiction is likely to be the cause of the spit and splutter. Beyond the point of stiction elimination, these symptoms may suggest a damaged or failing injector.

Solution: To clean out your gummed-up injectors, pour a dose of Stiction Eliminator; otherwise, a repair or replacement may be required.

Problem: Misfires can be instructed to the injectors when an electrical fault, such as an ICP sensor failure or if the FICM malfunctions, creating similar spit and splutter in the engine.

If you notice a lot of white smoke when you remove the oil cover, it could mean you have too much crankcase pressure.

Problem: When fuel, air, and moisture are driven past the cylinder rings and into the crankcase, this is known as ‘blow-by.’ Some blow-by is normal on any diesel engine due to the increased combustion pressure common to diesel engines, and when the pressure is too considerable for the piston rings to hold entirely. Excessive blow-by, on the other hand, might be produced by piston rings stuck in the bore.

Solution: Turning your oil filler cap upside down on the filler hole is one technique to see whether there’s too much blow-by. The cap blows off when the engine is running because the crank case is under too much pressure. Using Stiction Eliminator and Diesel Extreme to free up both sides of piston rings is a simple approach.

These piston rings must be replaced when blow-by is caused by worn piston rings, resulting in a misfire in the lower compression cylinder.

What is the best way to tell if my crankcase pressure is too high?

Not only can you monitor crankcase pressure with a vacuum gauge or manometer, but you can also use a scope and an accurate pressure transducer like the Pico WPS500.