Why the Temperature Difference?

By: Grid Michal

QuestionI have twin 7.4 MerCruiser inboards, freshwater cooled. They’re mounted approximately 40 inches apart. The dash temperature gauges both show a rock-steady 180 degrees at throttle. Call me crazy, but the exhaust manifolds that are to the inboard of each engine feel substantially warmer than the outboard manifolds. They’re certainly not close enough to be creating proximity heat. What could be causing this?

AnswerAs much as I believe in the value of tactile senses, I also am a firm believer that the mind can be fooled. Use a heat-sensing gun to get exact temperatures. Your “substantial” could be as little as 5 degrees, as you move from side to side trying to equalize the situation.


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