New to me. Went out first time and alarm sounded and hot light lit on the tach. Changed out the water pump and tstats and still does the same. Motor runs fine, only alarms above about 3800 RPM. Plenty of water from the telltale. Even after the alarm sounds the water from the telltale is not hot,and there is plenty of flow, it is barely warm. I ran today with the cowl off so as to feel the heads. I could keep my hand on them for a while before they got hot to me. I even unhooked the wires from the temp senders and the alarm still sounds.When I changed out the tstats last week I pulled a small peice of silicone from the opening. Previous owner perhaps had the same problem and changed out the water pump also( it appeard in good condition) I figured that that was the problem but nothing has changed. With a hose hooked up to the wash out and the tstats out I ran the hose at full pressure. I put a 5 gallon bucket to catch the water coming out under each stream of water from each tstat. One bucket filled a bit faster but only by about a 1/2 gallon of water. Before replacing the senders is there a way to test them. Suggestions eagerly awaited and appreciated. I am not so sure that the engine is in fact overheating. I can only test when in the water Because it runs and pumps water fine at low RPM's .