Is it necessary to replace the valve cover on a BMW?
3 Answers
It is necessary to replace the valve cover on a BMW. If the valve cover of a BMW car shows signs of oil leakage, it must be replaced immediately. Precautions for replacing the valve cover: Clean the contact surface thoroughly: When replacing, first completely clean the contact surface of the valve cover. Then, apply sealant based on the owner's preference. Replace after the engine cools down: When replacing, the car engine must be completely cooled before the valve cover can be replaced. Tighten the valve cover multiple times during installation: When installing the valve cover, tighten it diagonally in multiple passes. After securing one screw, secure the screw on the opposite diagonal. This prevents uneven stress on the valve cover gasket. If the valve cover is leaking oil, it must be replaced promptly. Within the warranty period, the valve cover can be replaced free of charge.
Last time my N20 engine leaked oil until it dripped onto the exhaust pipe and started smoking before I rushed to get it fixed. The mechanic said BMW's aluminum alloy valve cover tends to warp after about five years of use. When the rubber gasket ages, it leaks engine oil. In severe cases, the engine cover gets completely covered in sludge, and it can even contaminate the ignition coils. I've personally seen cars that weren't fixed—their underbody guards had accumulated a centimeter-thick layer of oil residue. The worst part is that oil leaking into the spark plug wells can cause misfires and engine shaking. Replacing the cover is definitely cheaper than a full engine overhaul, right? After all, the new covers are made with improved materials—mine hasn't leaked a drop of oil even after 20,000 kilometers.
For vehicles over three years old, it's advisable to check under the hood during each maintenance, especially around the cylinder head seams and ignition coil slots. My F35 initially had just a few oil spots which I ignored, but later I noticed a burnt smell at idle. Upon inspection, I found the spark plugs soaked in oil and rusted. The OEM gasket costs only 300 yuan, but in reality, the entire plastic cover needs replacement, with parts costing over 2,000 yuan plus the labor of removing the intake manifold. However, compared to the repair costs of a burnt oxygen sensor, this preventive replacement isn't expensive at all, especially since BMW's precision components can't withstand oil immersion.
