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I bought a 77 25hp Johnson, first it was backfiring and I discovered a crack coil and I think I was getting some blow by in the head gasket so I replaced that also and that cured the problem. The motor seems to run hot though, I replaced the impeller and thermostat and it spits water nicely. Took it out on the lake for about an hour today and ran in intervals of 10 minutes or so at 3/4 to full throttle. when backing down to idle it would stop spitting water for 15 seconds or so and just spit hot steam , then start pumping water again. Water is definitely hot. could keep my hand under if I really had to but would be uncomfortable. This doesn't seem normal to stop spitting water, My older 20hp mercury (70) and (74) never stop spitting water when backing from full to idle speed. any thoughts?
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