The bmw oil is one of the most common problems encountered by the owners of the n20 and b48 engines。
"a thousand miles of oil." "smoking the exhaust pipe blue smoke." i don't know. These descriptions are common in bmw friends. More worryingly, many of the owners of the cars went to the 4s store and received the answer: "recommended engine change is done", offering 780,000 or even 100,000。
First give me a bmw: most bmw oil problems do not require a change of engine. Specific reasons are found for the component-level maintenance, which may cost only a fraction of the sum。
This article begins with the criteria for calibration oil, and explains several common causes of bmw oil and the corresponding low-cost rehabilitation programme。
First, to judge: is your bmw really burning oil
The word "heavy oil" is used in the main mouth of the car — is the drop in the surface of the oil is the burner oil? Not necessarily。
Normal oil consumption: it is normal for any engine to consume a small amount of oil during operation. The official standard for bmw is consumption of no more than 0. 7 litres per 1,000 km of machine oil. If your consumption is within this range, it is normal and no maintenance is required。
Consumption requiring attention: if consumption exceeds 1 litre per 1,000 km, it needs to start paying attention. If more than 1. 5 litres or more are consumed per 1,000 km, it is generally possible to confirm that there is an abnormal problem with engine oil。
Quick self-measurement method: the fluid surface of the oil is capped after maintenance, and the fluid surface of the oil is inspected after a normal journey of 1,000 kilometres. Looking at the drop in the surface, it is possible to calculate consumption roughly per 1,000 km. This method is simple but effective。
Ii. Four main common causes of bmw oil
1. Pistol-ring card delay
This is one of the most common reasons for bmw n20 engine oil. The piston ring acts as a seal between the piston and the wall of the tank to prevent oil from entering the combustion chamber. However, if long-term low-speed travel, low-quality oil or maintenance breaks are too long, carbon is formed in the piston sink, which "stucks" the piston ring, rendering it inflexible and unable to bind it closely to the tatter wall, and the oil is burned out of the cracks into the combustion room。
The piston cycling card is characterized by a typical diagnosis: there is no visible blue smoke in the exhaust pipe at cold start, but after some time, the blue smoke will appear when the vent accelerates. This is due to increased engine loads after hot vehicles and increased volume of oil that enter the combustion room。
2. Aging gas-gate seals
Gas-gate seals are seals that prevent oil from permeating the combustion chamber along the gas-gate poles. The bmw engines work at high temperatures, and gas-gate seals are prone to hardening and cracking over a long period of time in high temperatures, with reduced sealing performance。
The typical characteristic of an ageing gas-gate seal is blue smoke in the exhaust pipe at cold start, and mitigation or disappearance after the hot car. As the oil leaked into the combustion room after a certain period of parking, the oil was burned when the cold started and blue smoke was used. The blue smoke is mitigated by higher oil temperatures, changes in viscosity and a decrease in leakage following the hot vehicle。
3. Fault of the waste gas valve (gas separators)
The role of the exhaust valve is to separate the oil and gas mixture from the curvature arc, to return the oil to the shell, and to allow the waste gas to enter the vent to burn again. If the internal membranes of the exhaust valve are broken or the efficiency of separation is reduced and the oil vapour cannot be effectively separated, it enters the vent directly with the exhaust gas and is burned in the combustion chamber。
The method of judging the failure of the waste valves: the examination of the interior walls of the vents indicates a decrease in the separation efficiency of the waste valves if there is a significant amount of sediment deposition. In some cases, the failure of the waste valve can also result in a lack of motor speed or a combination of too low acoustic failure codes。
4. Turbo pressurizer oil seal leakage
Turbo booster bearings require oil lubrication, which, if the turbine's oil is worn out, enters the middle cooler and the vent along the pressure booster's entry path and eventually enters the combustion chamber and is burned down。
(b) the determination of leakage of tanker seals: check the inner walls of the middle chiller into the gas pipeline and, if there is a visible oil membrane or droplet, the issue of tanker seals needs to be suspected. At the same time, it is possible to observe whether there are leakage marks in the turbine matrix。
Iii. Comparison of maintenance programmes: part scale repair vs replacement engine
If a piston card is confirmed to be slow: a clean-up solution can be tried first. The elasticity of the piston ring is restored through the injection of a special washing agent into the tank to soak the carbon accumulated in the piston sink. The cost of deregulated treatment is usually $23,000 for a period of 1-2 days. It would be more expensive to consider the replacement of piston rings in case of non-dismantling, but much less than the total replacement engine。
In the case of aging gas-gate seals: some of the models can replace gas-gate seals without unbundling the caps (using a specialized tool to compress gas-gate springs), which significantly reduces maintenance hours and costs. Of course, the specific exemption depends on the model and engine structure。
In the case of waste valve failure: replacement of the waste valve is sufficient. The price of the exhaust valve itself is not expensive, and the cost of working hours is reasonable, generally at a thousand dollar level。
In the case of turbine seals, depending on the circumstances, the option is either to repair the turbine pressurizer (replace the oil seal and bearings) or to replace the turbine pressurizer. The cost of repairs is usually between one third and one half of the total。
Four, practical advice for bmw owners
Regular maintenance, use of engine oil. Prevention of engine oil is more important than maintenance. Use oils of suitable viscosity levels and certification standards strictly in accordance with the mileage specified in the maintenance manual, and do not use low-quality oils to save money。
Run the highway occasionally. Long-term low-speed travel can easily generate carbon accumulation, and regular high-speed runs can help reduce carbon accumulation and indirectly reduce the risk of piston-ring card stagnation。
Increased oil consumption was observed, leading to accurate diagnosis. Don't take the idea of changing the engine as soon as you find the oil. A systematic check by experienced bmw maintenance technicians — starting with a simple waste valve check, starting with an assessment of the gas-gate sealing state, moving to a carbon stock check in the tank, gradually removing and finding the real cause of the malfunction。
The bmw oil is not terrible, but it is terrible to fix it blindly without finding the right reason. Accurate failure diagnosis, coupled with a reasonable maintenance programme, would be sufficient to solve the problem at reasonable cost。
The key to the maintenance of problems such as bmw is precision diagnosis and the choice of a bmw-focused, experienced, door shop where fewer circuits and less money are spent. For example, beijing's rule bmw is dedicated to making only one brand of bmw, located in west trade and compass. The founder of the project was a graduate in qinghua engineering and a former senior chinese product engineer in bmw, with a bmw-specific diagnostic program. They insist that they “can be replaced” and provide an open-ended 2-year kilometre guarantee at a 30-50 per cent lower cost than 4s。
