PURPOSE: To prevent hot wind from diffusing by forming the receiving part for the hot wind, passing through the convergence part of an exhaust manifold, from the inner wall of transmission, front side wall of engine, and auxiliary apparatus or the like, and installing an exhaust tube behind this receiving part.

CONSTITUTION: As hot wind receiving part 21 a space is formed which is bounded by the inner side wall of a transmission 11, the front side wall 10a of an engine 10, and an alternator 20 as auxiliary apparatus. The convergence part 23 of an exhaust manifold 22 installed at the front side of the engine 10 is arranged in a place near the inlet to this hot wind receiving part 21, and an exhaust tube 24 extending backward is fitted at this convergence part 23. Accordingly the cooling wind having passed through a radiator 19 flows around the manifold 22 to be led to the receiving part 21 in the form of a hot wind, and is exhausted to the down side while flowing along the exhaust tube 24. This eliminates diffusion of the hot wind into the inner expanse of the engine room to preclude heat damages.