An internal combustion engine comprising a cylinder block (1) with at least two cylinders (8) and at least two exhaust valves (12) per cylinder (8), a slit (28) in the cylinder block (1) between each pair of cylinders (8), and a cooling system which comprises an inlet opening (36) for cooling liquid (20), formed in the cylinder block (1), an outlet opening (42) for cooling liquid (20), formed in a cylinder head (2), a restriction member (34) which is arranged in the cylinder block (1) and guides most of the cooling water flow to an intake side (38) of the cylinder block (1), and cooling liquid channels (18a-18e) in the cylinder head (2) which are chiefly located on an exhaust side (40) of the cylinder head (2). The cooling liquid channels (18a-18e) open into the cylinder head (2) in an area between the exhaust valve seats (16) for each cylinder (8) and thereby regulate at the same time the flow and cooling around the cylinder liners (32) and between the exhaust valve seats (16).