An engine cooling system is provided. The engine cooling system includes a cylinder head including an integrated exhaust manifold that directs exhaust gases to an exhaust outlet port and a coolant passage surrounding the exhaust manifold. The engine cooling system further includes a cluster of separated exhaust passages for directing exhaust gases to the exhaust outlet port, the cluster including a drill hole disposed within material between the exhaust passages, the drill hole fluidically coupled to the coolant passage.