Today, the number of natural gas vehicles has an explosive growth. Many drivers have replaced their diesel vehicles with natural gas vehicles. However, due to the characteristics of gas vehicles, many problems that are not easily caused on diesel vehicles will happen easily on gas vehicles. And now the author would like to shares a case with you.

Several days before, a gas-powered tractor truck came to us for inspection due to its’ insufficient power. The driver complains its’ failure of a weak climb capability, and the bad performance for accelerating even on a smooth road. Besides, it was much slower than before. It was found through inspection that the bypass valve of the turbocharger exhaust gas turbine was leaking. As a result, the speed of the supercharger is insufficient, the supercharging pressure is reduced, and the power of the natural vehicle deteriorates, which is a basically problem that will frequently occurs in gas engines.

There are certainly many people will ask why gas engines are prone to this problem. This will start with the characteristics of gas engines. Gas engines use natural gas as a fuel. The ignition point of natural gas is 650 degrees, which is much higher compared with the 220 degree of diesel. Which leads to a higher gas engine operating temperature and exhaust temperature.

On the other hand, in order to make sure that the engine have a better low-speed performance, the exhaust gas volute of the turbocharger is comparatively small, so as to ensure the normal operation of the supercharger at a lower speed. When the engine speed increases and the exhaust pressure rises, the bypass valve will open to avoid excessive intake pressure caused by the over speed of the supercharger.

Considering the above two factors, the speed of the gas engine is higher than that of the diesel engine, and the exhaust gas temperature is also higher. The exhaust gas pressure is more likely to rise due to high temperature exhaust gas. At this time, the bypass valve of the supercharger must be operated frequently, even if throttle, bypass valve will also open. With high temperature and high pressure and frequent opening, the wear of the valve seat is exacerbated, and it is not strange it will cause a leak after a long time working.

However, at present, there is no better prevention methods for this problem. It is the only way to replace the supercharger volute or booster assembly to solve the problem. Therefore, we must pay more attention when using natural gas vehicles. If we find that the truck has problem with insufficient power, maybe here is the reason.