Why the cause of white smoke can be determined by oil loss via the valve guides
(1) The negative pressure of the intake manifold is high when the engine is idle, so oil is sucked into the combustion chamber (more…)
Automotive Diagnosis
Propeller Shaft Vibration and Sounds
Imbalance
Imbalance in the propeller shaft causes vibration or noise, like in tires. The propeller shaft turns faster than tires by the gear ratio of the differential gear. Therefore, the frequency of (more…)
Tire Uniformity Vibration and Sounds
Tire uniformity refers to uniformity of weight, dimensions and rigidity.
However, since uniformity of weight is ordinarily called “wheel balance” and uniformity of dimensions is called “run-out” uniformity (more…)
Run-out Vibration and Sounds
Since a tire is made by bonding together rubber, there is a in difference in the rubber thickness, the circumference of the tire is not a perfect circle.
Even if the tire is perfectly circular, if the (more…)
Wheel Balance Vibration and Sounds
Due to the weight unbalance of the rotating object, a centrifugal force is generated during rotation, which results in a vibrating force.
This vibrating force increases in proportion to the square of (more…)
Tires Vibration and Sounds
The vibrating force caused by tires can be classified into two cases; the tire itself generates the vibrating force and uneveness on the paved road cause a vibrating force.
Tire itself generates vibrating (more…)
Automotive Fan Noise
Fan noise produced by the cooling fans for the radiator, alternator, and others, become louder in proportion to their rpm.
The fan noise can be produced by fan blades cutting through the air, or by air (more…)
Other Components of Engine Vibration and Sounds
Engine Mounts
Although engine mounts are relatively small, they are important in controlling NVH.
They link the vehicle body to the engine, the largest source of vibration. It is through these mounts (more…)
Engine Intake and Exhaust System Vibration and Sounds
Intake System
Intake noise includes the pulsating sound of the air taken in and the resonance sounds.
A pulsating sound has a relatively high frequency. It is determined by the air volume, shape of the (more…)
Engine Imbalance due to Inertia
Vibrating forces due to inertia forces are caused by the crank mechanism and imbalance in the rotating object.
Among the inertia-caused vibrating forces, reciprocating mass can be balanced to a certain (more…)