MAINTENANCE MANUAL OF GW4D20/GW4D20B TURBOCHARGED DIESEL ENGINES
18
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
3. Reliability and Durability Index
3.1 Reliability
Reliability of the engine means the engine can work continuously and its normal working ability is not
influenced by malfunctions under the designed working condition. In China, the reliability of engine is
normally represented by non-stop malfunction times, stop malfunction times and number of major parts
and minor parts replaced during the warranty period (or insurance period).
The major parts include: the cylinder head, piston, piston ring, piston pin, connecting rod, connecting rod
bearing bush, connecting rod bolt, crankshaft, engine body, camshaft, intake and exhaust valves, valve
spring, rocker arm, high pressure fuel pump, oil pump gear, driving gear, turbocharger, etc. The rest are
minor parts.
3.2 Durability
The durability index refers to the total operation hours of the engine or the driving kilometers of the
vehicle from the initial use of engine to the first overhaul. It is the index that represents the service life of
engine. Now, the durability of the domestic small-sized high-speed diesel engine is 2000 ~ 3000 h, and
the high-speed internal combustion engine for vehicle is 100000 ~ 200000 km.
4. Low Public Hazard Index
The poisonous emissions and noises from engine are harmful to human health and have negative
influences on working efficiency, so China and other counties have established more and more strict
controlling standards to protect the normal ecological environment for human beings. The poisonous
gases produced by the engine during working mainly come from the exhaust gas, blowby from the
crankcase, and vaporized gases from the fuel tank, fuel pipe connector, etc. The exhaust gas from
engine contains many compositions, including CO
2
, steam, surplus oxygen, residual nitrogen, CO, HC,
No
x
, S0
2
and particles such as aluminide, black smoke, oil mist, etc.. and stinking gases such as
formaldehyde, acrolein, etc. The blowby from the crankcase mainly includes HC, CO and so on, and the
main vaporized gas from the oil tank is HC. The total amount of the above exhaust pollutants takes up
about 1
％
of the exhaust gas from the engine. Most of them are poisonous and harmful, with strong
pungency, a stinking odor and carcinogenesis.
There is no uniform international emission regulation at present, China and other countries have
established their own emission control standards to control the emission of poisonous CO, HC, NO
x
and
the smoke density.
China promulgated ―Law on Prevention of Air Pollution‖ in 1987 and then promulgated the GB engine
exhaust standard to limit the poisonous emissions from the engine. Compared with those of the
developed countries, the domestic controlling standards for poisonous engine emissions are looser, but
they will get stricter and stricter and will joint with the international standards gradually from the
perspective of its developing trend.
China promulgated
Regulation on Prevention and Control of Environment Noise Pollution
in 1988.The
engine is widely used as the power source, and its exhaust gases and noises have the largest
environmental pollution area, and therefore attracting more and more attention from the public.
