Automobile engine piston has no direction.

The piston of an engine has a direction. Pistons are marked forward, and when mounted, the mark or arrow on the top of the piston should be mounted forward, that is, towards the timing gears of the engine. The top notch of the piston is not symmetrical, so it needs to be installed in the right direction, otherwise the top of the piston will collide with the valve.

Piston and connecting rod are provided with a mark, and this mark is mostly forward (toward the direction of the gauge) mark. It should be known that the stress point and friction coefficient are different in different directions, so the forward-facing mark must be assembled in the correct direction (all facing the front of the body).

The installation of engine piston rings requires the use of special fixture, in the installation of the piston ring should pay attention to the installation sequence, some engine piston rings with three rings, including two gas rings and an oil ring, and some use four rings, including three gas rings and an oil ring. But the installation sequence is nothing more than from the bottom of the oil ring installed, and then in accordance with the third gas ring -- the second gas ring -- the first gas ring (silver) in the order of installation.