I sincerely hope that the case we encountered is accidental-but combined with past experience-
Early adopters always have a price.
Photo: I was so busy repairing the car that I forgot to take other people's photos and stole one.
Mr. X was just promoted to the first batch of 440i owners in China last year, but the coupe with spicy eyes only made him feel good for three months, and the worrying journey of seeking medical treatment began in late summer and early autumn last year. At that time, he suddenly found that his car would have a slight "click" sound when stepping on/putting down the accelerator.
In fact, it is not only when stepping on/putting down the accelerator, but also when the original R&D gear is switched. And it will be much better when it is cold, and it will be particularly obvious and frequent when the temperature is high.
In fact, the owner has made a lot of efforts. He ran N times in the BMW 4S shop at home, which tortured the technicians to death. Finally, the 4S shop claimed that the scientific name of the right engine foot was "engine suspension device".
Figure: Don't think that 440i things are hard to buy. In fact, many accessories can be used on the 335i.
The engine foot is a component that connects the car body and the engine, and its function is similar to our sole. The vibration generated by the engine will be absorbed and isolated by the feet. If our feet fail, our hips will feel high-frequency vibration, but under normal circumstances, our hips will not feel numbness caused by this vibration.
It's really safe to drive for a few days, but not for a few days. At this time, the shopkeeper went to the 4S shop again, and 4S was honest-the foot of the machine didn't change at all, but it was re-tightened.
How clever BMW is! With this abnormal noise, it is impossible to claim successfully. The reason why I want to tell the owner that I have "claimed" a robot foot is purely a spiritual victory method to fool customers.
Then you can only go to Zhihu and try your luck with King Wu Yue. ...
Going to the store for the first time
When I saw something strange, the 4S shop also ate a nose. Nature dare not neglect. I quickly made an appointment with the customer to go to the store to inspect the goods.
We quickly reproduced this abnormal sound, which was easily "excited" when the car was hot, but where did the sound come from? Our BMW homicide team can't make a judgment at the first time.
Of course, it's not useless. We basically conclude that the abnormal sound comes from the exhaust side of the engine, that is, the co-pilot side of the engine compartment. However, when we took out all the monitoring equipment, aimed at this area and tried to find this "click", we encountered heavy interference.
Compared with the engine noise, this abnormal noise is really too small.
You can only hear a lot of work noise in monitor headphones.
Seeing that the conventional means will fail, the major crimes unit can't help but think back about the fault itself:
Step on the accelerator, release the accelerator, switch R/D back and forth ... Click. ...
The working condition that can induce abnormal sound is a very common high frequency operation. From a conventional point of view, the vehicle has not changed before and after operation. But I have to say that there are still some changes in the engine compartment-for example, the engine will stir left and right.
Figure: If the engine is placed horizontally, it will stir back and forth.
Following this line of thought, if the "click" abnormal sound is caused by engine agitation, we divide the engine compartment parts into three categories and analyze them respectively-
When stirred up, the body parts must be motionless, and naturally they will not make any noise;
The accessories on the machine body and the stirring engine are relatively quiet, and it is not easy to make a sound;
The accessories connected between the engine and the car body will have obvious relative movement when stirred up, and there is a probability of abnormal sound;
What are the parts that connect the car body and the engine?
Engine foot, intake pipe, exhaust pipe, cooling pipe and oil supply pipe. ...
When we began to check these parts, we suddenly made a major discovery: the bolts on the exhaust side were not tightened, and many bolts could be easily unscrewed by hand! Comprise an exhaust manifold fixing bolt, a turbine bracket bolt, a three-way catalytic clamp bolt and an exhaust pipe lug bolt. ...
This discovery is very shocking!
We were careless and told the customer in detail that we tightened the bolts on the exhaust side, but we were very uneasy-I'm afraid it's not that simple! Customers are naturally suspicious. Finally, we failed to resist the customer's stubbornness and seriously changed the foot according to his request. Of course, we use the engine foot of the Lunford brand, which was originally branded by BMW, and the price is only 1/3 of the original price.
During the period, customers were also worried that there was a problem with Amway's "Aiwen" anhydrous antifreeze at the time of the first insurance, and we also changed it back to the original antifreeze. I heard that the love story of Egg King is going to be written. All I know is that his penis was burnt.
Come to the store for the second time.
Sure enough, less than a week after returning, the abnormality of customer feedback came back. The customer had to come to the Shanghai store for the second time, but this time, he told me a message: he went to the 4S store to have a "heart-to-heart" conversation with someone, and the technician there honestly admitted that the bolt on his right foot was loose. ...
All right! No bolt is tightened on the right side of the whole engine! No one left behind!
Photo: The bolt shown by the arrow is loose after a few days.
We checked these loose bolts again and found that all the bolts were tightened, only the three-way catalytic clamp bolt was loose again! Is it because this slender bolt will be shaken loose when using the car every day, and then it will make a "click" noise?
Photo: As an advertisement, Le Tai's glue (not just thread glue) is still very good.
When designing a machine, bolts with weak fastening force may loosen on parts that often vibrate. In order to solve this problem, engineers will take some anti-loosening measures, such as coating thread glue, using check washer or lock nuts. We decided to take extra anti-loosening measures for this suspected bolt!
Picture: Can you still see it?
Sorry, we bought some lock nuts and washers for 1 yuan, and then screwed them all on. We hope that through this bondage, we can express our surging mood at the moment. After all, it is very rare for the original factory not to tighten the bolts, and there are design defects here-it is normal for the mood to fluctuate!
Remind technicians that it is more convenient to check and fasten the fixture by rotating the fixture 90 degrees and rotating the bolt from the lower side.
Concluding remarks
It's been more than 1 month, and Mr. X's 440i has no abnormal sound. Our handling should be effective (though a bit excessive). We also inquired about BMW's technical announcement, and there is no relevant content. However, similar problems have been found in other 3.0T models, and BMW officials suggest applying sealant on bolts to achieve the corresponding effect.
Although this fault has no effect on driving safety, some car owners may not notice it at all. However, we believe that it is quite surprising that the German manufacturing industry, which is famous for its rigor, can break through the layers of defense and flow into the market after making such low-level mistakes. I hope that BMW will make up for it in time in a responsible attitude towards users.
Otherwise, Nuo Nuo will get back at you next time!
Buy a car and see Nuo Nuo by word of mouth.