What is the reason for the high temperature of automobile engine after overhaul?

Of course, we should check whether the cooling system is faulty first. Another problem that often occurs after overhaul is uneven cylinder head. If the cylinder head is ground too much due to insufficient flatness, the working area of the cylinder will become smaller, and the water temperature will be too high, especially if it runs fast, it will be easier to get up (it is better in cold weather and hotter in hot weather). As for the clearance between piston ring and cylinder, it will not lead to high water temperature, but. The mechanic tricked you, and this phenomenon can't run well. If the cylinder head is worn out, the best way is to replace it, but you really don't want to replace it. Add a cylinder head gasket. But doing so may lead to easy cylinder pulling, low compression ratio (because you don't know how much it has actually been ground), and the engine will work at high temperature for a long time, which is fatal to the engine. Of course, it depends on how high the temperature is, such as 90 degrees, which is nothing.