Problems with excessive oil consumption in Diesel Engines

Diesel engines offer excellent mileage, durability, longevity and power to get your tough jobs done. With proper operation, care, maintenance, and proper planning for eventual overhauling of certain wear components, a diesel engine can last a very long time. Sometimes problems sneak up on you and it is important to understand what is going on with your equipment. It is either that or getting eating alive by predatory mechanics that smell blood in the water. Being an informed and adept operator of your diesel engine can ensure it operates optimally for as long as possible and prevent dishonest shops from taking advantage of you.

One of the most common indicators of an underlying problem present in your diesel engine is excessive oil consumption. Every diesel engine will have a natural and acceptable amount of oil consumption. Problems arise when the oil consumption exceeds these thresholds.

Some common reasons for excessive oil consumption are as follows:

• Oil Consumption Cycle – Engines tend to consume more oil if they are brand new or freshly overhauled. One must follow a proper break in process to ensure optimal function after an overhaul. Once broken in properly, oil consumption will subside to normal operating levels until enough wear reemerges in the internal components, notifying that the engine is starting to wear down ( this can be after many hundreds of thousands of miles)

• Heavier Duty Environment – Heavy loads, extreme conditions, mountainous terrain, marine applications and other factors that contribute to a Diesel Engine increasing the strain on the engine and thus contributing to more oil consumption.

• Viscosity of Oil – The lower the viscosity of the oil, the higher the consumption. Keep this in mind when performing oil changes.

• Oil Change Frequency – Try to stay on a strict regimen of oil changes according to OEM specifications. After an overhaul make sure to alter your frequency for at least the first two oil changes after a rebuild. Ideally you want to change your oil once after 500 miles and then again at half your usual interval. So if you normally change oil every 15,000 miles, change it at 7,500 miles on the 2^nd oil change. After that you can go back to normal oil change interval frequency. You can learn more about this process in our post about “Optimal Oil Change Intervals after an Overhaul”

• Leaking Oil – In some case excessive oil consumption can be explained by something as simple as a leak. Usually from the valve cover gasket or oil pan gasket.

• Burning Oil –Carbon build up in the cylinders prevents the rings from moving freely. This will cause oil to get past the rings and burn. Using higher quality oil can mitigate this problem.

• Contaminated Oil – Debris will accumulate in the oil if you do not change the oil and oil filter often. This will cause oil passages in the piston rings, and pistons to clog. This will increase oil consumption and lead to premature wear on bearings, liners, pistons, and piston rings.

• Excessive amount of oil & oil pressure in crankcase – Having to much oil and oil pressure in the engine can lead to oil burn and subsequent carbon build-up on components.

• Worn Timing Components – If something in the engine timing system is off, it can lead to the creation of an air vacuum that draws large amount of oil in the cylinder. Worn timing gears that throw off valve and crankshaft timing are a great example.

• Improper Ring Gap Clearance – If rings are out of spec and do not allow for proper gap clearance with the cylinder walls you will have a situation with scuffing and scoring of the cylinder walls and the piston rings. This will also increase oil consumption and possibly lead to engine failure.

• Worn or Cracked Piston Ring – Another variation of improper ring gap clearance can arise if rings have worn out or were cracked during installation. This will lead to oil consumption, carbon deposit build up, and loss of power and compression. Sometimes a piston is in good shape and can be re-used as long as new rings are installed to ensure a proper seal and compression.

• Stuck Rings – Make sure rings are always within spec for their gap clearances. Also assure that they are clean and free from any damage or cracks. Use quality oil or even a break in oil or additive. This will help ensure proper compression and power and avoiding potential scuffing and scoring.

• Restricted Air Flow – Issues with oil consumption can lead to carbon buildup in air passageways and air filters. This will draw more oil into the combustion chamber and subsequently lead to more oil consumption and wear on components.

These are all issues and causes arising from excessive oil consumption. If they are not addressed, it can lead to operation of a diesel engine with low oil levels which can lead to a vicious cycle causing even more oil consumption, carbon buildup, premature wear on components, power loss and overall poor engine performance. Stay ahead of these issues to ensure your engine’s longevity and optimal performance.

Other factors to consider:

1. Excessive bearing clearance in the turbocharger

2. The oil return line on the turbocharger is blocked

3. Worn injection pumps

4. Abnormal combustion and fuel flooding

5. Valve stem seals and valve guides are worn

6. Incorrect piston protrusion 

If you are experiencing any of these symptoms or issues, reach out to us and one of our knowledgeable parts technicians will advise on the best course of action.