Abstract: A breather chamber structure of an internal combustion engine in which condensation of vapor within the breather chamber is prevented, the number of required parts is small, the space efficiency is superior and enlargement of the whole engine can be avoided is provided. In an internal combustion engine having auxiliary machinery attached to a side wall of a cylinder block (3) by means of an auxiliary machinery bracket (10), a breather chamber (20) is formed by the side wall of the cylinder block (3) and the auxiliary machinery bracket (10) between the side wall and the bracket, and a cooling water passage (40), (41) is formed on at least one of the side wall of the cylinder block (3) and the auxiliary machinery bracket (10) swelling in the breather chamber (20).

Abstract: An auxiliary part mounting bracket for an in-line multi-cylinder engine. An oil pump, an auto-tensioner, an alternator, a water pump and a compressor are preassembled on the auxiliary part mounting bracket to form an assembly. This assembly is fixed to a side of the engine cylinder block by six bolts. One bolt is threadedly inserted into the cylinder block through a space defined between the upper oil pump and auto-tensioner and the lower alternator and water pump; two bolts are threadedly inserted into the cylinder block through a space defined between the upper positioned alternator and water pump and the lower positioned compressor. Thus, it is possible to enhance the assembling operation, when the plurality of auxiliary parts are fixed to an engine body through the auxiliary part mounting bracket.