Why is the engine leaking oil? Actually, it's the sealing ring.
In the last issue of the article, we conducted a comprehensive inspection on the maintenance links of E46 of the newly bought second-hand BMW 3 18i of the Tang Dynasty, and found that almost all parts of the engine that could leak oil leaked. After struggling for a long time, the Tang Dynasty, who just got his salary, finally got down and said, "Change all the sealing rings!" " "
● Learn to distinguish between oil leakage and oil leakage.
At the beginning of the article, I want to tell you the concepts of oil leakage and oil leakage: oil leakage refers to oil dripping caused by damage, deformation or assembly problems of some engine parts, and the leakage speed is fast. If this happens, it must be repaired as soon as possible.
In fact, oil leakage is only a minor problem, and some oil leaks can't even be called faults. Because of the strong permeability of engine oil, it is normal to naturally leak a small amount of engine oil under the strong pressure in the cylinder, but from the probability analysis, most of the oil leakage is caused by rubber sealing rings. Small-scale oil leakage can be completely ignored, and large-scale oil leakage belongs to the category of oil leakage and must be paid attention to.
● Sudden oil leakage/large area oil leakage after maintenance.
Many car owners should have encountered this situation. One day, the car was fine, and the next day, when they looked again, they found a big pool of oil on the ground. They are usually caused by deformation, the bottom of the oil pan mop is broken or the machine filter is not tightened. After this problem occurs, check the oil level immediately and go to the repair shop for inspection at the first time.
In many forums, you can see that some netizens posted that the engine of the new car just mentioned leaked oil. Some cars are indeed caused by assembly process and design defects, and more often, the sealant on the outside of the joint of parts melts and falls off because of high temperature. In this case, you just need to clean it.
-Cleaning before maintenance.
In fact, many oil stains are not oil spills, but accidentally spilled or flowed out when refueling or changing oil. It usually appears around the oil filler and mechanical filter. These oil stains often belong to thick old mud, which has almost no luster. Therefore, in this case, it is necessary to clean the oil first, open it for a period of time, and observe whether there is oil seepage.
When adding new oil, the spilled part should be cleaned up in time, otherwise it may be mistaken for oil leakage in the future. Generally speaking, if this oil stain is discovered long after the oil change, it will have old traces, dark color, accompanied by a lot of dust and debris, rather than bright liquid.
E46 Replace the bonnet gasket
● E46 oil leakage
For this old E46, there is no doubt that the rubber sealing ring must be aging, and it seems to leak oil more than once. By observing the leakage position, the valve cover gasket, oil pan gasket, servo motor gasket, tru e air pump gasket and solenoid valve gasket were finally locked and replaced, and almost all the real leakage places were there.
-bonnet gasket
Under normal circumstances, due to the aging of rubber gaskets, vehicles over three years old are prone to this problem. If the leakage is not serious, it can be cleaned regularly.
After removing the valve cover, clean it thoroughly. When replacing the sealing ring, clean the oil stains around the valve cover and cover it with non-woven fabric. If dust and foreign matter enter the exposed valve chamber, it will cause abnormal internal wear of the engine and cause secondary damage to the engine.
-Oil pan
The oil pan of most models is protected by the engine lower guard plate, so a little jacking will not cause any problems to the oil pan. If it leaks, be sure to check whether it is a filter screen and an oil drain.
It is worth mentioning that if your car is insured with car damage insurance, you should immediately call the insurance customer service phone to report the case and take photos to leave a certificate. The insurance company will bear the corresponding cost of towing, repairing and even changing oil.
E46 Replacement of various sealing rings and summary
-Brake the vacuum pump
The brake pump of E46 is driven by camshaft and lubricated with oil. It is located behind the cylinder head and outside the valve chamber near the firewall. This kind of real empty pump oil leakage will not actually cause any functional failure, but when the oil occasionally drops on the hot three-way catalytic converter, it will smoke and smell like burning engine oil.
Most brake vacuum pumps of vehicles rely on the rear end of throttle to obtain vacuum. Because N46 engine has variable valve lift technology, the throttle valve is always open, and the traditional brake booster pump can't get enough vacuum from the intake pipe, so BMW has equipped an independent brake vacuum pump for N46 engine, although it has been solved.
-Solenoid valve
At present, variable valve timing technology has been widely used in engines, and major automobile manufacturers have their own engine valve technology names, such as BMW VANOS, Toyota VVT-i, Honda i-VTEC, Audi AVS and so on. Its function is to optimize the engine intake and exhaust system, ensure that the intake and exhaust can better meet the requirements of various working conditions, and then improve the engine efficiency.
-Servo motor
-Eccentric shaft
In the valve control system, the eccentric shaft sensor detects the position of the eccentric shaft. By measuring the rotation angle of the eccentric shaft, the actual parameters are provided for the adjustment function. The eccentric shaft is adjusted by a servo motor controlled by an electronic valve, and its measuring angle range is 180.
● Maintenance price
We have reported the maintenance of E46 in 4S shops and repair shops before, and the price quoted by 4S shops is about 4000 yuan. But this time, on the premise of using all the original accessories, we chose the second-class repair shop, and the quotation was only 2000 yuan, which was almost twice as bad.
● Be careful! Oil leakage can also cause spontaneous combustion!
Speaking of which, I believe some netizens will say that my car has leaked into the river and can still drive normally. These problems don't need to be fixed at all, but are they?
As we all know, oil itself is not flammable under normal circumstances, because its ignition point is as high as 200 degrees Celsius or above. But when the working temperature of the turbocharger reaches several hundred degrees Celsius, the situation is completely different. Especially when the leaked oil is mixed with impurities such as dirt, the ignition point is reduced and the fire risk is further increased. Especially for some classic cars, the circuit is seriously aging, and it is likely to catch fire and spontaneously ignite after encountering oil pollution.
● The sealing ring is intact. Why is the oil leaking?
-Is the oil leakage in the bonnet caused by screws?
The screw on the valve cover only plays a fixing role, and the rubber ring is the real seal. According to the vehicle maintenance manual, the valve cover screw has a specified torque and should be tightened with a torque wrench instead of brute force. Too tight or too loose will lead to leakage. There is one more detail to pay attention to. There is a sequence when tightening screws. Most cars screw four screws in the middle and then four screws around. The most correct method is to pre-tighten each screw before locking. Similarly, if the oil pan leaks oil, check whether the oil drain screw is loose.
-What's with the oil leak in the new car?
In many forums, you can see that some netizens posted that the engine of the new car just mentioned leaked oil. Some cars are indeed caused by assembly process and design defects, and more often, the sealant on the outside of the joint of parts melts and falls off because of high temperature. In this case, you just need to clean it. If it still leaks, directly seek compensation from the manufacturer.
● Summary:
In fact, the problem of oil leakage is not big. Regular inspection and more attention can avoid a lot of unnecessary troubles. Vehicles that leak oil during the warranty period will resolutely go to the 4S shop to claim for replacement. If the vehicle is over-insured and the oil leakage is not serious, then the oil can be cleaned at intervals.
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