Advanced Automotive Fault Diagnosis
tải về 7.07 Mb. Chế độ xem pdf
|
LÔØI NOÙI ÑAÀU, ledklok
- Điều hướng trang này:
- 2.4.5 Road test
- Normal driving speeds of 20 to 80 km/h (15
| 2.4.4 Vibration conditions
Clicking, popping or grinding noises may be noticeable at low speeds and be caused by the following: ● inner or outer CV joints worn (often due to lack of lubrication so check for split gaiters); ● loose drive shaft; ● another component contacting a drive shaft; ● damaged or incorrectly installed wheel bear- ing, brake or suspension component. The following may cause vibration at normal road speeds: ● out-of-balance wheels; ● out-of-round tyres. The following may cause shudder or vibration during acceleration: ● damaged power train/drive train mounts; ● excessively worn or damaged out-board or in-board CV joints. The cause of noise can often be traced by first looking for leaks. A dry bearing or joint will pro- duce significant noise. 1. Inspect the CV joint gaiters (boots) for cracks, tears or splits. 2. Inspect the underbody for any indication of grease splatter near the front wheel half shaft joint boots. 3. Inspect the in-board CV joint stub shaft bear- ing housing seal for leakage at the bearing housing. 4. Check the torque on the front axle wheel hub retainer. 2.4.5 Road test A vehicle will produce a certain amount of noise! Some noise is acceptable and may be audible at certain speeds or under various driving condi- tions such as on a new road. Carry out a thorough visual inspection of the vehicle before carrying out the road test. Keep in mind anything that is unusual. A key point is to not repair or adjust anything until the road test is carried out. Of course this does not apply if the condition could be dangerous or the vehicle will not start! Establish a route that will be used for all diag- nosis road tests. This allows you to get to know what is normal and what is not! The roads selected should have sections that are reasonably smooth, level and free of undulations as well as lesser quality sections needed to diagnose faults that only occur under particular conditions. A road that allows driving over a range of speeds is best. Gravel, dirt or bumpy roads are unsuitable because of the additional noise they produce. If a customer complains of a noise or vibration on a particular road and only on a particular road, the source of the concern may be the road surface. Test the vehicle on the same type of road. Make a visual inspection as part of the prelim- inary diagnosis routine prior to the road test; note anything that does not look right. 1. Tyre pressures, but do not adjust them yet. 2. Leaking fluids. 3. Loose nuts and bolts. 4. Bright spots where components may be rub- bing against each other. 5. Check the luggage compartment for unusual loads. Road test the vehicle and define the condition by reproducing it several times during the road test. During the road test recreate the following conditions. 1. Normal driving speeds of 20 to 80 km/h (15 tải về 7.07 Mb. Chia sẻ với bạn bè của bạn:
|