The front oil seal of the crankshaft has been clean and leak-free for several years. However, the rear oil seal on the generator side frequently leaks and requires repeated repairs. Once replaced, it continues to leak. Many people only know to simply replace the oil seal, which treats the symptoms but not the root cause. Today, I will explain all the root causes, core triggers, the authenticity of the oil seal, standard installation techniques, and the ultimate solution for this problem.
1. Why is the rear oil seal on the generator side prone to leaking?
Most people only see "the oil seal is broken". The real core reason is vibration. The front end of the crankshaft only drives the pulley and fan, with a light load and smooth operation, with almost no vibration. However, the rear end of the crankshaft directly connects to the generator, which is the load-bearing end of the entire unit: 1. Even a slight deviation in alignment will cause the engine and generator to have a slight deviation in coaxiality, and the coupling will generate impact with each rotation, resulting in continuous radial movement at the rear end of the crankshaft. The lip of the oil seal cannot stably adhere to the shaft neck, the sealing oil film breaks, and long-term leakage occurs. 2. Multiple vibrations combined cause the oil seal to rapidly fatigue. The bearing clearance of the generator is large, the rotor has poor dynamic balance, the on-site load fluctuates frequently, and in addition, the foundation bolts are loose and the shock absorbers are aging. All resonances are concentrated at the tail of the crankshaft, and the rubber of the oil seal is subjected to high-frequency stress for a long time, gradually relaxing, deforming, and failing. 3. Frequent changes in electricity load will generate pulling forces on the crankshaft from front to back, causing slight wobbling. The lip edge of the oil seal rubs against the shaft neck back and forth, and for a short time, grooves are worn out. 4. High-temperature environment. Rubber becomes hard, its elasticity decreases, and its vibration resistance deteriorates over time. By the way, some technicians are accustomed to shortening the spring, which will exacerbate the aging of the oil seal.
2. The unit body failure aggravates the oil seal leakage
In addition to the vibration problem, the unit's own working conditions are also a key reason for leakage: 1. The pressure in the crankcase is too high, the respirator is blocked, and the oil gas separator fails, resulting in a large amount of gas leakage from the piston ring.
2.Wear and tear of the crankshaft journal. The journal is scratched, rusted, has burrs, and the surface is not smooth, making the oil seal not fit properly. 3. Daily use and assembly issues, such as excessive oil addition, long-term high temperature operation, deformation of the rear cover, uneven force during screw tightening, all accelerate the damage of the oil seal.
3. Skills for identifying the authenticity of the oil seal
Many re-repair cases of leakage are not technical issues, but accessory issues. High-quality replicas look the same, but the material is completely substandard, not resistant to high temperatures, not wear-resistant, and not resistant to oil. 5 precise identification methods: 1. Look at the workmanship. The genuine product has clear characters, regular edges, and no burrs; counterfeit products have blurry printing, many rough edges, and rough workmanship. 2. Touch the rubber texture. The genuine product uses special temperature-resistant rubber, with a smooth, soft, and resilient feel, and quick rebound. Inferior oil seal rubber is hard, has a poor feel, and is prone to aging and failure under high temperature. 3. Look at the built-in spring. The genuine spring is uniform in thickness, has sufficient tension, and is neither loose nor uneven. Counterfeit springs are thinner and have poor elasticity, and will eventually loosen and fail to hold the crankshaft journal. 4. Look at the vulcanization process. The genuine product is formed as a seamless whole without gaps or glue. Inferior oil seals are mostly assembled, and are prone to layering and glue separation later. 5. Check the anti-counterfeiting traceability. Genuine products have official anti-counterfeiting codes that can be traced by batch number; high-quality replicas have no valid anti-counterfeiting information.
4. Standard installation techniques
Seven components, three parts for installation. Even if the original factory oil seal is installed incorrectly, it will still be scrapped! 1. Do not install dryly. Before installation, the lip edge and the position of the spring must be coated with high-temperature lubricating grease to prevent the lip edge from being scratched during the initial start-up. 2. Use special tools for vertical pressing. Do not directly strike or skewly press in. It is necessary to use a matching sleeve and apply vertical and uniform force to ensure the oil seal is installed flatly. 3. Thoroughly clean the journal before installation. Remove burrs, rust spots, and sharp edges on the journal to prevent scratching the new oil seal. 4. Control the standard pressing depth. Pressing too deep or too shallow will change the sealing angle and affect the sealing effect. 5. Firmly tighten the end cover diagonally and evenly to prevent the end cover from deforming, being skewed in force, and squeezing the oil seal, causing the sealing failure.
5. Complete solution for thoroughly curing the oil seal leakage
1. Adjust the coaxiality of the engine and generator to eliminate the source of vibration;
2. Inspect the coupling buffer gel, generator bearings, and the foundation bolts of the unit, and completely eliminate resonance;
3. Regularly clean the breathing device of the crankcase to prevent high-pressure oil from spilling out of the box;
4. Always use genuine high-temperature-resistant oil seals and avoid using inferior parts;
5. Strictly follow the standardized installation procedures to avoid assembly faults caused by human factors.
Summary
The oil seal at the rear of the crankshaft of the gas generator is leaking oil. This is definitely not a single sealing component failure. It is the combination of five factors - vibration, high temperature, air pressure, component quality, and installation process - that has caused this problem. Simply replacing the oil seal without addressing the root cause will result in repeated oil leakage. Identifying the problem and conducting targeted repairs can lead to a one-time and complete solution.