1. A mechanical seal face and a mechanical seal ring of the automotive pump mechanical seal. It is ideal to combine a carbon mating ring with a ceramic or sic seal face for the combination has the small abrasion,good thermal conductivity and mechanical strength and no corrosion to each other.A liquid film existing between the mechanical seal face and the mating ring can work as a lubrication no matter what kind of materials are combined. The spring load and the fluid pressure are joined together to seal the interface between them. Too large a specific pressure of the seal faces will not do good to the fluid film so that the heat will increase or the seal face and the mating ring wear each other too earlier. If the specific pressure/closing force is too low the interface will increase so that a big leakage will occur.The statistics of the failure of automotive pump mechanical seals shows that 80%-95% failure is caused by the friction of the seal faces and mating faces. The precision of the seal faces,the choice of the seal face materials, the end-face specific pressure can decide the working time of the automotive pump seals concerning the seal construction, the springs and fluid pressure.
2. The installation of automotive pump mechanical seals is here referred to as not only the installation of the mechanical seal but also the installation of the mechanical seals and the other parts of pumps. While the automotive pump mechanical seals are assembled each part of the mechanical seal should be kept clean and non-destructive.If the mechanical seal surface has some defects the seal will leak.
3. Pump shaft axial distortion.A certain specific pressure on the seal face and the mating seal face can make the mechanical seal work so the pump shaft cannot distort axially too largely.The axial force which the pump impeller produces while rotating will destruct the sealing of the mechanical seal and sometimes the mechanical seal face and the mating face will depart so that the leakage will take place. it is vital to control the axial distortion of the pump shaft and the axial interface between the pump shaft and the bearing should not be larger than 0.13mm. The axial balance design is very important.
4. The large vibration of an automotive pump mechanical seal.The automotive pump mechanical seal vibrates too largely and the seal face and the mating ring will not seal the fluids.The large vibration lies in the other parts of pumps, for example,the bad pump design, the bad work of the parts and the precision of the shafts.
5. The pump shaft deflection is too large. The pressure on the end seal faces will be not the same if the pump shaft deflects too largely. try to reduce the cantilever length of the pump shaft and make an option of the right material for the shaft.
6. The steam or vapour. At the entrance of the pump the steam corrosion will occur if the device system is not good. A good number of bubbles will occur when the steam happens in the cooling water, which will shock the outside surface of the seal ring and the mating ring to be damaged and make the fluid film not form a sustainable flowing film and the seal ring and the mating ring will friction in a dry way and in the end the seals will not work properly
7. The precision of mechanical process is not tight. The deficiency of the precision is here referred to as not only the precision of the mechanical seal but also the precision of the other parts of the pump including the impeller,pump body and belt wheel and etc.