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490发动机的曲轴止推间隙是0.05～0.28毫米,它是靠后轴颈长46~(+0.08)毫米,后轴承座宽40_(-0.12)~(-0.05)毫米及止推垫片厚3_(-0.05)毫米来保证。使用一段时间以后,允许该间隙在0.5毫米以内。如果曲轴轴向窜动量过大,会造成发动机窜气、烧机油。当止推间隙大于1.5毫米时,止推垫片会脱落,因而造成曲轴、缸体等重要零部件的磨损。这种故障的原因:一是止推垫片自然磨损严重;二是止推垫片装反,因该垫片只有一边是耐磨合金层,所以装反后曲轴止推肩与钢片的一边接触,加剧磨损。一般新车出现止推垫片脱落的故障,多是这个原因。修理时,首先应测量有关零件的磨损情况。若更换止推垫片后,不能保证规定的止推间隙时,应修理。修理时,可用加大厚度的止推垫片。如果没有此
490 engine crankshaft thrust clearance is 0.05 ~ 0.28 mm, which is by the rear journal length 46 ~ (+0.08) mm, the rear bearing width 40 _ (- 0.12) ~ (-0.05) mm and the thrust washer thickness 3_ (-0.05) mm to ensure. After use for a period of time, the clearance is allowed to be within 0.5 mm. If the crankshaft axial movement is too large, it will cause the engine gas channeling, burning oil. When the thrust gap is greater than 1.5 mm, the thrust washer will fall off, resulting in crankshaft, cylinder and other important components of the wear and tear. The reason for this failure: First, thrust washer natural wear and tear serious; Second, thrust washer mounted anti, because the gasket is only one side is wear-resistant alloy layer, so installed anti-crankshaft thrust shoulders and steel side Contact, aggravate the wear and tear. General new car thrust washer failure occurs, mostly for this reason. Repair, should first measure the wear and tear on the parts. If the replacement thrust washer, can not guarantee the provisions of the thrust gap, should be repaired. Repair, available to increase the thickness of the thrust washer. Without this