Advanced Automotive Fault Diagnosis
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LÔØI NOÙI ÑAÀU, ledklok
- Điều hướng trang này:
- 2.4.7 Sources of engine noise
- 2.5 Electrical diagnostic techniques 2.5.1 Check the obvious first!
| 2.4.6 Engine noises
How do you tell a constant tapping from a rattle? Worse still, how do you describe a noise in a book? I’ll do my best! Try the following table as a non-definitive guide to the source or cause of engine or engine ancillary noises. Noise description Possible source Tap Valve clearances out of adjustment, cam followers or cam lobes worn Rattle A loose component, broken piston ring or component Light knock Small end bearings worn, cam or cam follower Deep knock or thud Big end bearings worn Rumble Main bearings worn Slap Worn pistons or bores Vibration Loose or out of balance components Clatter Broken rocker shaft or broken piston rings Hiss Leak from inlet or exhaust manifolds or connections Roar Air intake noise, air filter missing, exhaust blowing or a seized viscous fan drive Clunk Loose flywheel, worm thrust bear- ings or a loose front pulley/damper Whine Power steering pump or alternator bearing Shriek Dry bearing in an ancillary component Squeal Slipping drive belt 2.4.7 Sources of engine noise The following table is a further guide to engine noise. Possible causes are listed together with the necessary repair or further diagnosis action as appropriate. Sources of engine Possible cause Required action noise Misfiring/backfiring Fuel in tank has Determine wrong octane/ which type of cetane number, fuel was last put or is wrong type in the tank of fuel Ignition system Check the faulty ignition system Engine temperature Check the too high engine cooling system Carbon deposits Remove the in the combustion carbon deposits chamber start to by using fuel glow and cause additives and misfiring driving the vehicle carefully Timing incorrect, Check the which causes timing misfiring in the intake/exhaust system. 12 Advanced automotive fault diagnosis Valve train faulty Valve clearance too Adjust valve large due to faulty clearance if bucket tappets or possible and incorrect renew faulty adjustment of valve bucket tappets – clearance check cam condition Valve timing Check the valve incorrectly adjusted, timing and valves and pistons adjust if are touching necessary Timing belt broken Check timing belt or damaged and check pistons and valves for damage – renew any faulty parts Engine Pistons Disassemble the components Piston rings engine and faulty Cylinder head gasket check Big end and/or main components bearing journals Ancillary Engine Check that all components components or components are ancillary secure, tighten/ components loose adjust as required or broken Renew if broken 2.5 Electrical diagnostic techniques 2.5.1 Check the obvious first! Start all hands on diagnostic routines with ‘hand and eye checks’. In other words look over the vehicle for obvious faults. For example, if the bat- tery terminals are loose or corroded then put this right before carrying out complicated voltage readings. Here are some further suggestions that will at some point save you a lot of time. ● A misfire may be caused by a loose plug lead – it is easier to look for this than interpret the ignition waveforms on a scope. ● If the ABS warning light stays on – look to see if the wheel speed sensor(s) are covered in mud or oil. tải về 7.07 Mb. Chia sẻ với bạn bè của bạn:
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