One of my Honda BF45s has a weaker cooling water telltale outlet stream than the other, and the casing gets hotter to touch. After 10 minutes running (out of the sea) at 2,000 rpm, the metal part of the casing (either side of the engine oil drain hole) gets quite hot to touch. I havn't measured the actual temperature of the casing, but I reckon it's between 60 and 70 deg. C. Similar to a hot central heating radiator.<br /><br />There's also an interesting cycle in the flow of outlet water. Letting the cooling water telltale outlet stream run over my hand, it feels fairly hot to touch, then it suddenly gets cool. At the same time the volume of water coming out through the propellor hub increases a lot. After a few seconds, the volume of water coming out through the hub reduces again, and the cooling water telltale outlet stream gets hot again for a few seconds, before the whole cycle starts again. It keeps doing this over and over while the engine is running at 2,000 rpm. I'm guessing its the thermostat opening and closing.<br /><br />My questions are A) given that I can only just bear to keep my hand on the hot engine casing, is the engine running too hot? and, B) Should the thermostat be opening and closing continuously at only 2,000 rpm? and, C) If something is restricting the flow of cooling water in the engine, can anybody suggest where to look for the problem?<br /><br />Here's some of the things I have tried already: The short hose leading from the engine block to the cooling water telltale outlet is not blocked, and neither is the outlet itself, nor the nipple on the engine block that this hose attaches to. The impeller is in good condition. The thermostat is new. The water pressure my garden hose supplies to the water inlet is strong. I have taped over the water inlet under the cavitation plate.<br /><br />Any help you guys can give would be much appreciated.<br /><br />Thanks.
)<br /> Turn the water on and you should see a strong exit out of the telltale. If not, then turn the water off and pull the t-stat. turn the water back on and you should get water gushing out the t-stat hole. If you get water out, then you know that section of the cooling passage is clear. If not then a blockage might exist in the later half of the cooling passages.<br /> Try this first and let us know. It should only take about 15 minutes to do this test.<br /><br />Nav