Views: 76 Author: Site Editor Publish Time: 2025-05-30 Origin: Site
We found that 80% of repeated oil leakage accidents are caused by parts quality problems.
This article will use a maintenance case to explain the important role of correctly selecting valve covers in preventing oil leakage problems.
Recently, a vehicle equipped with a BMW N20 engine broke down due to oil leakage. The owner reported that the valve cover had just been replaced, but it leaked oil again. After inspection, the technician found that the sealing gasket of the new valve cover was not elastic enough, which made it unable to fit tightly with the cylinder head. In addition, the material strength of the valve cover was insufficient, and it deformed at high temperature, resulting in sealing failure. After comparison, it was confirmed that there were problems with the quality and precision of the previously installed valve cover. After replacing the valve cover that met the standards, the oil leakage problem was effectively solved.
If oil leakage occurs shortly after replacing the valve cover, it is likely related to the quality of the replaced valve cover.
Long-term exposure to high temperatures can cause the valve cover gasket to age and lose its elasticity, resulting in reduced sealing performance.
Valve covers made of plastic are easily deformed by high temperatures, which can cause seal failure.
The exhaust valve is responsible for exhausting the exhaust gas in the crankcase. If the exhaust valve is damaged, it will cause an imbalance in internal pressure, resulting in oil leakage.
Improper installation, such as misaligned gaskets or uneven bolt torque, will result in poor sealing.
- Check the valve cover for any signs of damage, such as cracks, chipping, or warping.
- Make sure all components, including valve cover gaskets and seals, are intact and properly installed in their respective slots.
- Measure and record engine pressure.
- Check the engine for carbon deposits. If the carbon deposits are serious, remove the carbon deposits and replace any aged parts.
- Clean the throttle body and remove any residual oil.
- Refer to the figure and remove the old valve cover in the reverse order of 20-1. Before removing the bolts, loosen them 180°.
- Thoroughly clean the cylinder head mating surface and bolt holes. Do not use sealant.
- Before installation, apply a small amount of engine oil to lubricate the threads of all bolts.
- Check if there are locating pins on the cylinder head. If so, align them with the corresponding positions of the valve cover first.
- Tighten the bolts in the specified order using a torque wrench according to the bolt tightening sequence shown in the figure.
- Align the valve cover bolts (1-20) with the corresponding positions on the cylinder head and tighten them 180° first. Then, use a torque wrench to tighten them twice with a torque of 5Nm and 9Nm respectively. Make sure all bolt holes are aligned correctly.
- Use self-tapping screws to secure the camshaft sensor seal with a torque of 5.5Nm. Do not use the wrong specification or over-tighten.
- Measure the engine vacuum pressure and make sure it is correct. Otherwise, there is a risk of leakage in the valve cover.
- If the oil filler cap leaks, replace the oil filler cap seal.
Nebod provides high-quality valve covers, gaskets and exhaust valves for car owners. These parts are made of high-temperature resistant and elastic materials and are manufactured strictly according to standard processes to effectively prevent oil leakage. During installation, always ensure that the gasket is perfectly aligned with the cylinder head and tighten the bolts evenly with the specified torque to avoid the risk of oil leakage caused by improper installation.
