Dear BMW owners, BMW powder, friends who care about BMW models and want to buy used BMW cars, I believe that everyone is no stranger to the oil leakage of the valve cover. It is also confirmed that the BMW that does not leak oil is not a real BMW. As a second-hand Z4 car owner, I have just finished repairing the valve cover of my favorite car, and I would like to share my personal views on the common problem of oil leakage in the valve cover. Welcome to have an interactive discussion in the message area to make our car-loving and car-playing life happier.
At present, the engines used in the mainstream BMW models 1 Series, 3 Series, 5 Series, 7 Series, X1,X3,X5 are all N52,N54,N55,N20 (the latest B48 and B58 used in new models are out of the scope of this article because they have not leaked oil from the valve cover for a long time). Basically, the dividing line is 12 models, all of which were in-line 6-cylinder engines and 2.5L N52B25; 3.0L N52B30; 3.0T ones are N54B30,N55B30. Most configurations after model 12 basically use 2.0T N20B20 high and low power, and the high configuration uses 3.0T N55B30. All these engines have the common problem of valve cover oil leakage. You can check the engine model on the vehicle registration certificate (green copy), or check the engine model of your car on an APP such as a home.
Why does the valve cover leak oil? On the one hand, the valve cover and the engine block are sealed by a layer of rubber gasket, which is what we often hear. In the long-term high-temperature working environment, the rubber becomes hard and loses its sealing performance. At this time, there will be a layer of oil stains around the valve cover, which is called slight oil leakage. On the other hand, BMW makes the valve cover made of plastic (most of the engine valve covers are made of aluminum alloy). The working temperature of the engine is very high, and the plastic valve cover will be deformed in a long-term high-temperature environment. After deformation, the seal between the valve cover and the engine block is not tight, resulting in oil leakage. At this time, it can be clearly seen that there is black oil accumulation around the valve cover, even dripping down, dripping on the exhaust pipe or the engine belt. Generally, the valve cover pad will age for 2-3 years, resulting in oil leakage, and the valve cover will age for 6-8 years, resulting in oil leakage. (I use oil leakage and oil leakage to distinguish the layers of oil leakage in the valve cover, ranging from slight oil leakage to serious oil leakage)
What is the impact and harm of oil leakage or oil leakage from the valve cover, and is it necessary to repair it immediately? First of all, you can be sure that oil leakage has no effect on the engine working condition and vehicle use, except that there will be a layer of oil stains on the engine surface, which will become more and more serious with the passage of time. Personally, I suggest that you don’t rush to repair when oil leakage first occurs, continue to use it, and observe it regularly (mine has already appeared oil leakage when I just bought it, so I didn’t rush to repair it, but only repaired it after two years of continuous use. Why don’t you repair it urgently? Simply put, it doesn’t affect the use, and it is economical and easy to consider. From a professional point of view, I will explain it slowly below. However, when the valve cover becomes leaking oil, especially when the oil has dripped on the belt or transmission, it is recommended to repair it in time. Although it doesn’t affect the working condition of the engine, the temperature of the exhaust manifold is very high (at least above 300 degrees), and the oil drops on the exhaust pipe will evaporate immediately, and there will be a strong oil smell floating into the car. No one wants to sit in BMW and enjoy the blue sky and white clouds but always smell a pungent oil smell. What a spoil the scenery. Speaking of this, some cautious friends may ask whether there is a possibility of spontaneous combustion, which is extremely unlikely. The ignition point of the oil is very high, about 2000 degrees above, and the engine cannot reach this temperature when running. In addition, the oil drips on the belt of the pulley. Because the belt is made of rubber, the high-temperature oil will affect the service life of the belt and even cause combustion.
Is it troublesome to repair the oil leakage of the valve cover? There are two maintenance schemes for oil leakage of valve cover, one is to replace only the valve cover gasket, and the other is to directly replace the valve cover assembly (which includes the gasket). The working procedures of the two methods are the same, so the working hours are basically 300-800 yuan (with different repair shops and qualifications), but the price of accessories is much different. The price of a set of original valve cover gasket is 200-400 yuan (with different delivery channels), while the original valve cover assembly is 1800-2600 yuan, and the replacement parts imported from Germany are 800-1300 yuan. However, this is not the case. Generally, the valve cover will leak oil in 3-4 years, and the valve cover will age and deform in 6-8 years when the mileage reaches about 80,000, which will lead to serious oil leakage. Here, I mentioned that there is no need to repair it in a hurry when oil leakage first occurs. Apart from saving trouble, another reason is that if your car leaks oil after being used for 4 years, this is caused by the aging of the valve cover, and the valve cover may not be deformed, but it is also aging. If only the valve cover gasket is replaced, it won’t be long before the valve cover becomes aging and the assembly needs to be repaired and replaced, so the money for replacing the gasket before will be wasted, so the direct isotonic oil will become oil leakage, and then the valve cover will be replaced directly once after the valve cover is deformed. In the same way, if there is a serious oil leakage, it is not possible to replace the valve cover pad only, because the valve cover is deformed, which will lead to oil leakage. If the maintenance master tells you that you can change the pad first,If it doesn’t leak, it’s okay. If it still leaks, replace the assembly. In fact, he knows very well that he will basically have to change the assembly again (that’s what he wants, you know). . . . )
How to choose 4S shop and repair shop during maintenance? Can it be completely solved after maintenance? Whether to go to a 4S shop or a repair shop for maintenance is a matter of opinion, depending on your pockets. The cost of replacing the valve cover assembly in a 4S shop is about 5000-8000 yuan (some old cars can enjoy a discount, for example, my Z4 can enjoy a 7.5% discount, so please consult the local 4S shop for details). If you can afford it, you don’t have to worry about it, so you can go directly to the 4S shop for maintenance. Of course, the 5,000 yuan that you will buy a BMW is certainly affordable, but it also depends on whether it is necessary. Considering the cost performance, I suggest that it is enough to find a reliable and qualified repair shop for maintenance, because the number of BMW cars is very large now, and most of the BMW cars that have reached the age limit have replaced the valve cover. Those who are famous in the local area must have repaired a lot, and the maintenance masters are very experienced in this. There is no technical difficulty in replacing the valve cover itself. It can be handled well for experienced middle-level workers and above. Can it be completely solved after maintenance? The answer is unfortunately, no. The reason is very simple because the newly replaced valve cover is still made of plastic, which will age and deform after a long time. In fact, replacing it is equivalent to doing an oil maintenance, and it will be replaced when it reaches the service life again. Therefore, you don’t have to worry too much about the quality of the accessories used in the repair shop. As long as you don’t shoddy them, you can sell them as original parts. Of course, it doesn’t mean that the accessories can’t be used.It’s just that you spend more money. I still have great confidence in a conscientious repair shop. After all, the service industry depends on word of mouth. There is a difference of more than 1,000 yuan between the accessory parts and the original parts, and there are different opinions about the difference in use. Everything is true, and it is not a problem to use the accessory parts for two or three years (because many riders are thinking of selling them for two or three years when they buy used cars, which is quite good (∩_∩)O).
It’s so long-winded that it’s the first time to share it. If there are any problems in the grammar or professional knowledge of the article, please correct me. You are also welcome to discuss and exchange in the message area. If you pay attention to the praise of friends and get more responses, it’s ok. I’ll share the process of replacing the valve cover and the rubber gasket of the oil filter seat with my Z4 in the next issue.
