Causes Of High Exhaust Pressure Of Diesel Generator Crankcase

Excessive exhaust pressure under diesel generators is a common fault of diesel generators. There are many reasons for the excessively high exhaust pressure of the crankcase of the internal combustion engine. The main fault analysis and diagnosis are as follows:

1. Severe wear of the piston ring or cylinder liner. When the piston ring or cylinder liner is severely worn, there is no seal between the piston and the cylinder liner. During the compression and expansion process of the diesel engine, the small gap between the cylinder liners will increase the exhaust pressure of the diesel generator, thereby increasing the exhaust pressure of the diesel generator.

The following phenomenon: serious exhaust under the respirator, insufficient diesel generator power, may produce blue smoke.

2. Corresponding piston ring. Although the piston ring is not worn, if the ring ports are completely aligned, a large amount of high-pressure gas will enter the crankcase during the compression and expansion process, causing the pressure of the crankcase exhaust gas to rise.

At the same time: if the diesel generator exhausts severely, the fuel consumption will increase, and blue smoke may appear in the exhaust.

3. The piston ring is stuck or broken. Adhesion, breakage or loss of elasticity of the piston ring will cause the cylinder to be tightly sealed, and the combustion gas will enter the crankcase, which greatly increases the exhaust pressure of the crankcase.

Next step: the crankcase exhaust pressure is large, the diesel generator is smoking, the power is insufficient, the abnormal noise in the cylinder, etc.

4. If the cylinder is corroded or pulled, the cylinder will lose its seal and naturally generate exhaust pressure. Accompanied by noise, black smoke emission, insufficient power or diesel generator unable to rotate and other phenomena.

5. The crankcase breather fails.

(1) The breathable membrane or the piston is faulty. If the breather diaphragm or the piston of the breather fails, the crankcase and the airflow will lose balance. Due to the internal and external pressure difference, the amount of contaminants in the crankcase increases.

As a result: fuel consumption rises, blue smoke emissions are serious, but there is basically no impact on power.

(2) The small vent hole of the ventilation device and the atmosphere is blocked. Blocking a small hole in the air breather will cause the inside of the crankcase to lose balance with the atmosphere. In the same way, due to the internal and external pressure difference, the emission of crankcase exhaust gas also increases.

As a result: fuel consumption rises, blue smoke emissions are serious, but there is basically no impact on power.

6. Too much oil. Excessive oil will increase the exhaust pressure of the crankcase. That is also due to the limited space of the crankcase and excessive oil. The crankshaft connecting rod and other high-speed moving parts severely collide with the oil, splash out, produce oil mist, and cause the crankcase exhaust pressure to increase.

From this: the crankcase exhaust pressure is too high and the oil level is too high.

7. The blow-by in the air compressor is serious. When the piston ring of the air compressor is severely worn, the compressed gas in the air compressor will randomly flow into the crankcase, causing the pressure of the crankcase exhaust gas to increase. If the diesel generator piston ring, cylinder liner, respirator, etc. are inspected without problems, the exhaust gas pressure of the crankcase is still relatively large, and the air compressor needs to be inspected accordingly.

The resulting phenomenon is: the exhaust pressure of the crankcase increases, the oil consumption rises, the pressure of the air system of the equipment is slow, and the oil exists. At this time, check the quality of the air compressor, dredge the air system, and appropriately replace the air compressor (piston ring, etc.) or air circuit safety valve and other components.

8. Because the piston ring or cylinder liner is related to other factors, the exhaust pressure of the crankcase varies greatly.

When the piston ring or cylinder liner is worn, the combustion gas enters the crankcase. Therefore, the exhaust gas from the crankcase has a strong burning smell, while other factors do not have this smell.

Piston ring or cylinder liner factors make the oil black in a short time, while other factors make the oil black. Piston ring or cylinder liner slippage will cause insufficient power of diesel generator, black smoke, abnormal noise in the cylinder, etc., but the above phenomenon does not exist in channeling due to other factors.

9. The high exhaust pressure of the crankcase is harmful.

(1) Increased oil consumption. 

(2) Diesel generators emit serious blue smoke

(3)  It is easy to cause carbon deposits on the top of the piston or carbon deposits in the piston ring groove, which may cause cylinder pulling failure.

(4)  Contrast the closed cycle crankcase breathing system (immediately directly Introducing the exhaust pipe of the respirator into the intake pipe of the diesel generator can easily cause ablation of the top of the piston.

Jiangsu Starlight Electricity Equipments Co.,Ltd. has 64 sales and service departments across the country, providing users with one-stop service of design, supply, debugging and maintenance at any time. Looking forward to your inquiry, please send email to us for details sales@dieselgeneratortech.com