Other possible reasons include problems with the oil pump, rod and main bearing clearances, camshaft end play, or CAM bearings and lifters.

其他可能的原因包括油泵问题，杆和柱轴承之间的空隙，凸轮轴停止工作或者凸轮的方位和升降等。

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End face with a gap, no boss butt is refers to the upper and lower casing left a certain gap between the upper and lower main chord rod end face at the same time contact.

端面有间隙、无凸台对接是指在上、下套管之间留有一定间隙，上、下主弦杆端面同时接触对接。

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End face with a gap, no boss butt is refers to the upper and lower casing left a certain gap between the upper and lower main chord rod end face at the same time contact.

端面有间隙、带凸台对接外形是指在标准节上部主弦杆上焊有定位凸台，定位凸台伸人另一标准节主弦杆内，上、下套管之间留有一定间隙配合定位。

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