Why does a three-cylinder engine shake after three years?
3 Answers
The reasons for a three-cylinder engine shaking after three years include aging or loosening of engine mounts and fuel system malfunctions. Details are as follows: Fuel system malfunction: Using an incompatible fuel grade can cause severe engine shaking, as lower fuel grades have poorer anti-knock properties. Alternatively, blockages in the fuel tank vent, fuel tank switch, fuel filter, or the fuel line between the tank and carburetor can restrict fuel supply, leading to an overly lean air-fuel mixture and engine shaking. The solution is to refuel at reputable gas stations and use the manufacturer-recommended fuel grade. Aging or loosening of engine mounts: Engine mounts are rubber blocks between the engine and chassis designed to reduce vibrations during engine operation and secure the engine. Once the mounts age or loosen, both the vehicle body and engine will experience abnormal shaking. The solution is to replace the engine mounts.
I have a deep personal understanding of the three-cylinder engine starting to vibrate after three years. Due to the inherent imbalance of the three-cylinder design compared to four-cylinder engines, the crankshaft only has a cylinder firing every 120 degrees of rotation, resulting in discontinuous energy transfer. It's not very noticeable when the car is new because the rubber engine mounts are still elastic and can absorb vibrations. However, after about three years, the rubber typically hardens and cracks, allowing vibrations to directly transmit into the cabin. There's also the issue of carbon buildup—carbon deposits on the piston tops affect the compression ratio, leading to unstable combustion during ignition. Before my car's warranty expired, I replaced the engine mounts with reinforced ones and also cleaned the throttle body and fuel injectors. Now, the steering wheel hardly vibrates at all. Additionally, I recommend using fuel additives regularly to slow down the rate of carbon buildup.
My three-cylinder car has been running for three and a half years, and since last winter, it shakes so much at red lights that even the tea cup wobbles. The mechanic said it's mainly due to aging in several areas: the engine mounts have hardened and lost their damping effect, like shoes without insoles; the aging ignition coils cause misfires, as if one cylinder is slacking off; and carbon buildup in the throttle body restricts air intake. Additionally, the large temperature differences in our northern region accelerate rubber component aging. After replacing the engine mounts, the improvement was significant. Later, I started adding a bottle of the original fuel additive every 5,000 kilometers, and now even cold starts are much smoother. Actually, driving more on highways can help clean carbon deposits, but it's not easy for commuters.
