Hi I have a Mercury 115 that the top cylinder is getting significantly hotter than the other 3. The top one is hot but can still be held with your hand. The rest are lukewarm. Any ideas?
How warm should the water be coming from the tell tale hole? The water is only slightly warmer than the lake water. Also the other 3 cylinders are cool to the touch, about room temperature. The top cylinder is hot, but can hold my hand on it. Is this normal or any ideas on what may be causing the issue?
Your pee comes off the exhaust plate and its a indicator and tells you nothing about engine cooling. If impeller is weak even though you think its peeing good its possible the block is not fully filling at idle.Thus top cylinder warmer.....has killed many a TOP motor
Thanks Faztbullet, I will replace the waterpump impeller today. What temp should all the cylinders be? Should they be cool to the touch? The thermostat is 120 degrees. I appreciate all your help!