Greetings,

Trying to determine the best plumbing configuration for my bellhousing dual oil cooler set up. I'm using one cooler for engine oil and the other for the transmission. Typical heat exchanger rules of thumb suggest in on the bottom and out on the top to sweep out any trapped air. Additionally typical heat exchanger fluid flow is counter flow, fluids moving in oppposite direction. For the transmission this is doable as the starboard side cooler has water flowing from top to bottom which means the oil can enter on the bottom and exit on the top. As for the engine oil, water is flowing from bottom to top which puts the oil in top and out bottom following convention thinking. Can anyone tell me how Mercury plumbed the cooler on the port side and starboard side as I believe they used both sides for engine oil. Any other opinions on in / out - top / bottom are welcome.