一些搅拌车司机反映，跟朋友同时购买的同一款搅拌车，自己的车辆在使用一段时间后发动机就会出现问题，可是朋友的车辆发动机却没事，这到底是怎么一回事呢？一起来了解一下吧。

Some mixer truck drivers reported that the same mixer truck they bought with their friends would have problems with the engine of their own vehicle after a period of use, but the engine of their friends' vehicle was OK. What is the matter? Let's learn about it.

1、气门的光磨

1. Smooth grinding of valve

在小型混凝土搅拌车的维修中，如果气门出现烧蚀、麻点及凹陷时，均应进行光磨，一般是在光磨机上进行，作业时需要注意四个问题：一是保证气门头与杆部同心，否则应先校直；二是光磨辆在能磨出完整的锥面的前提下是越小越好；三是尽量提高表面光洁度；四是气门杆端部凹陷应予以磨平。

In the maintenance of small concrete mixer truck, if the valve is ablated, pitted and dented, it should be polished, generally on the polishing mill. Four problems should be paid attention to during the operation: first, ensure that the valve head and the rod are concentric, otherwise it should be straightened first; Second, on the premise that the smooth grinding vehicle can grind a complete cone, the smaller the better; Third, try to improve the surface finish; Fourth, the depression at the end of the valve stem should be polished.

2、气门导管的铰销

2. Hinge pin of valve guide

气门杆与气门导管配合间隙是决定气门导管使用寿命的关键，因此当更换新的气门导管时，铰销时应严格掌握好配合间隙，使用各搅拌车车型规定间隙的下限，可有效延长使用寿命。

The fitting clearance between the valve stem and the valve guide is the key to determine the service life of the valve guide. Therefore, when replacing the new valve guide, the fitting clearance shall be strictly controlled during the hinge pin. The lower limit of the clearance specified by each mixer truck model can effectively extend the service life.

3、气门的研磨

3. Grinding of valves

气门的研磨分为两种情况：一是气门与气门座只有轻微麻点，不需要光磨和铰销时的研磨；二是气门与气门座均经过光磨和铰销后的研磨。

The grinding of valves can be divided into two situations: first, the valve and valve seat have only slight pockmarks, which do not require polishing and grinding when hinge pins are used; Second, the valve and valve seat are polished after polishing and hinge pin grinding.

前者先用足金钢砂研磨，将麻点研磨掉后，再用细金刚砂研磨，后涂上机油研磨，直至密封符合要求，宽度符合规定为止。后者只有密封性达不到要求时才进行研磨，但操作时一定要注意，不要过分用力，严禁将气门上下敲打，否则将出现凹形砂痕，影响维修质量。

The former shall be grinded with full gold steel sand first, and then the pockmarks shall be grinded with fine carborundum, and then coated with engine oil until the sealing meets the requirements and the width meets the requirements. The latter can only be grinded when the sealing property fails to meet the requirements. However, attention must be paid during operation to avoid excessive force. It is strictly prohibited to knock the valve up and down, otherwise concave sand marks will appear, which will affect the maintenance quality.

混凝土搅拌车发动机出故障不可怕，可怕的是维修不正确，那发动机的性能只会越来越差。

The failure of the concrete mixer engine is not terrible, but the terrible thing is that the maintenance is not correct, and the performance of the engine will only get worse and worse.