发动机汽缸内的异响可归纳为活塞敲缸声、活塞销敲击声、活塞顶撞击缸盖声、活塞顶撞

发动机汽缸内的异响可归纳为活塞敲缸声、活塞销敲击声、活塞顶撞击缸盖声、活塞顶撞

击声、活塞环敲击声、气门敲击声及汽缸爆震声等几种

1、活塞顶与汽缸盖的撞击声

活塞顶撞击汽缸盖的异响为“嗒嗒嗒”连续不断的金属敲击声，高转速时尤为明显。其异响声源在汽缸上部，其声音坚实有力，且汽缸盖有震动。其主要原因有以下几种。

（1）曲轴轴承、连杆轴承及活塞销孔严重磨损，配合间隙严重超标，在活塞行程变换的瞬间，活塞在惯性力的作用下，顶部撞击汽缸盖。

（2）因更换活塞时误装其他类似规格的活塞，或伪劣产品，其活塞销孔中心线至活塞顶面的距离大于原活塞，使活塞到达上止点时，由于超高而碰撞汽缸盖。

在行驶途中，若遇到此类情况，急救办法是，卸下汽缸盖，加上一个汽缸垫，使缸盖升高而不致再发生碰撞。但有修理条件时，应立即进行修理，恢复其良好的技术状态。

2、活塞环部位的异响

活塞环部位的异响主要有活塞环的金属敲击声、活塞环的漏气响声及积碳过多引起的异常响声。

（1）活塞环的金属敲击声响。发动机长期工作后，汽缸壁遭到磨损，但汽缸壁上部与活塞环接触不到的地方却几乎保持着原几何形状与尺寸，这就使汽缸壁生成了一个台阶。如果用的是旧缸垫或是更换的新缸垫偏薄，工作中的活塞环就会与缸壁台阶相碰撞，发出一种钝哑的“噗噗”的金属碰击声。若发动机转速升高，该异响也会随之增大。另外，若活塞环折断或活塞环与环槽间隙过大，也会引起较大的敲击声。

（2）活塞环的漏气响声。活塞环弹力减弱，开口间隙过大或开口重叠，汽缸壁拉有沟槽等均会造成活塞环漏气。其声响为一种“喝喝”或“嘶嘶”声，严重漏气时则发出“噗噗”的声音。其诊断方法是，在发动机水温达到80℃以上时熄火，这时可向缸内注入少许新鲜干净的机油，摇转曲轴数圈后，重新启动发动机，此时若异响消失，但不久后又出现，则可断定为活塞环漏气。

（3）积碳过多的异常响声。积碳过多时，缸内传出的异响是一种尖锐的声音，由于积碳被烧红，发动机有点火过早的症状，而且不易熄火。活塞环部位积碳的形成，主要是由于活塞环与汽缸壁密封不严，开口间隙过大，活塞环装反，环口重合等原因，造成润滑油上窜，高温高压气体下窜，在活塞环部位燃烧，致使形成积碳甚至粘住活塞环，使活塞环失去弹性与密封作用。一般更换规格合适的活塞环后，此故障即可排除。

3、敲缸声

敲缸，指的是活塞在工作行程开始的瞬间，或者是活塞上行时，活塞在汽缸内产生的摆动，其头部和裙部与汽缸壁相碰撞而发出的“当当”或“嗒嗒”的异常声响。如果是“当当”声响，多为汽缸壁润滑不良所引起，此时可向缸内滴入少许机油，再启动发动机，若异响减轻或消失，即说明异响确为润滑不良造成的。如果是“嗒嗒”声响，同时排气管冒蓝烟，一般是由于活塞与汽缸壁间隙过大的缘故。产生上述情况的主要原因有以下几方面：

（1）若只在冷车启动后有这种现象。运转达正常水温时即自行消失，是因为活塞与缸壁配合间隙偏大，冷车时活塞又有收缩，使两者配合间隙进一步增大，从而出现明显的敲击声。机温升高后，活塞膨胀，间隙趋于正常值

Abnormal sound can be summed up in the engine cylinder piston Knocking sound percussion piston pin, piston top, hit the cylinder head sound piston contradict

Thud, piston rings percussion, valve knocking and cylinder knock several

1, the top of the piston and the cylinder head crash

The top of the piston to hit the cylinder head Sound of Da Dada "a continuous metal percussion, e specially in high speed. Its different sound source to the upper cylinder, the sound is solid and strong, and the cylinder head vibration.

The main reason are the following.

(1) severe wear of the crankshaft bearings, connecting rod bearings and piston pin hole, with the gap is excessive, an instant transformation in the piston stroke, the piston inertia force, the top hit the cylinder cover.

(2) due to the replacement of piston mistakenly loaded piston of similar specifications, substandard or counterfeit products, the piston pin hole centerline to the piston top surface of the distance is greater than the original piston, the piston reaches TDC, the ultra-high collision cylinder cover.

Driving on the way, encountered such a situation, first aid, to remove the cylinder head, plus a cylinder pad, so that the cylinder head rise without collision. Repair conditions, should immediately repair, restore its good technical condition.

2, piston ring parts of the abnormal sound

Abnormal sound of the piston ring parts of the main piston ring metal percussion piston rings leak sound and carbon deposits caused by excessive abnormal noise.

(1) piston rings of metal percussion sound. Engine after working a long, cylinder wall has been wear and tear, but the Ministry of the cylinder wall and piston ring of the reach of almost maintained the original geometric shape and size, which makes the cylinder wall to generate a new level. If you are using the thin old cylinder head gasket or replace the cylinder head gasket, piston rings will work with the cylinder wall, the steps collide, issued a blunt and dumb "pop" metal rattle. If the engine speed increases, the abnormal noise also increases. In addition, if the piston rings broken or piston ring and ring groove clearance is too large, will cause a large percussion.

(2) piston rings leak sound. The piston ring stretch weakened, opening the gap is too large or openings overlap the cylinder wall pull grooves, etc. will cause the piston rings leak. The sound for a "drink" or "h issing" sound serious leak when issued the "pop" sound. Diagnostic methods to turn off the engine water temperature above 80 ℃, then inject a little fresh, clean oil to the cylinder, crank the crankshaft a few laps after the restart the engine, At this point, if the abnormal sound disappears, but soon after can be concluded that for the piston ring leak.

(3) coke too many abnormal noise. Carbon deposition is excessive, the cylinder spread of abnormal sound is a shrill voice, due to the carbon deposition was red-hot, the engine ignition premature symptoms, but not easy to turn off. Piston ring parts of the coke formation, mainly due to the piston ring and cylinder wall Mifengbuyan, opening the gap is too large, piston rings installed anti collar coincidence reasons, resulting in lubricants channeling under high temperature and high pressure gas channeling, piston Central parts of the combustion, resulting in the formation of coke or stuck piston rings, piston ring loses its elasticity and sealing effect. Generally replace the appropriate specifications of piston rings, this failure can be ruled out.

3, Knocking sound

Knock, refers to a piston working stroke of the moment, or piston row, issued by the piston in the cylinder of the swing, the head and skirt and cylinder wall collision "Dangdang" or "blah" abnormal sound. Dangdang "sound, and more for the poor lubrication of the cylinder wall to the tank to drip a little oil, and then start the engine, if the abnormal sound to reduce or disappear, abnormal sound is indeed caused by poor lubrication. "Blah" sound, the exhaust pipe to take the blue smoke, generally due to the piston and cylinder wall clearance is too big reason. The main reason for these are the following:

(1) if only after the cold start of this phenomenon. Running up to the normal water temperature when away on its own, because the piston and cylinder wall with the gap is too large, cold car piston another contraction, both with the gap is further increased, thereby percussion. Machine temperature rise after the piston expansion, the gap tends to normal