More chaotic. When the meshing clearance of the timing gear is too small, it will emit a metal friction whistle, which will increase with the increase of engine speed. When the timing gear is seriously worn, the above phenomenon will also occur. When you touch the valve cover with your hand, you can obviously feel the vibration of your body and feel the numbness of your hand. The common causes of abnormal sound in the meshing process of timing gears are:
① The lubricating oil path is blocked, resulting in poor lubrication, dry friction and abnormal sound of the timing gear.
(2) Improper assembly or gasket is too thin and the gap is too small. During maintenance and repair, the cam timing gear assembly is skewed and uneven.
The boss rubs against the flange, resulting in sharp metallic abnormal sound.
③ The gear meshing clearance is too large, and when there is impact load, the tooth surfaces collide with each other, resulting in abnormal sound.
④ The timing gear has low machining accuracy and burr, or the tooth surface is peeled off during use, and the gear pair is in poor contact.
⑤ The fixing bolt of the timing gear flange is loose, the gear moves axially, the center of the shaft and hole deviates, the gear meshing is uneven, and the gear shakes.
It makes irregular noise during operation.
⑥ The camshaft is bent, deformed and loosened in use, which destroys the parallelism of the timing gear pair and causes early wear.
Loss, and produce abnormal sound.
Overhaul of abnormal sound of timing gear: If it is suspected that the timing gear has abnormal sound, you can contact the timing gear cover with a stethoscope for auscultation.
The noise is more obvious. Make the engine speed rise and fall, if there is a rolling sound of "click, click", it is that the gear gap is too large; if
Metal rubbing sound is an abnormal noise friction caused by poor lubrication and tight fit of parts. There will even be intermittent noise when idling.
The sound is messy at high speed, which is the deflection of timing gear; There are different growls at idle speed and high speed, indicating that the gear clearance is too small.
When the backlash of timing gear is too small, the sound is even and can be used continuously; If the backlash is too large and there is knocking sound at a stable speed, replace the timing gear (slight noise is allowed when the engine speed changes).
The axial clearance of camshaft is too large, so it should be overhauled and adjusted according to the specified value. Lubricating oil nozzle (that is, spray hole) is blocked, so it can be used widely.
Dredge the scalp needle, but don't poke it too much to avoid reducing the oil pressure. When replacing timing gears, it is best to replace gear pairs in pairs and use red.
Check the contact surface with Danyou. If there is no unilateral looseness, the tooth gap is evenly engaged. Tooth with contact mark distribution not less than 1/3.
Full length, and not less than 1/4 tooth height, tooth surface contact trace is not less than 2.5mm from the edge, otherwise it should be adjusted or repaired. Disassembly and assembly
When shifting gears, be sure to turn the crankshaft with a hand crank to make the ignition timing marks on the timing gear pair match and align, so as to avoid safety accidents.
Improper installation leads to inaccurate ignition of the engine.