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Hi I have a dt 85 that I have a problem with over heating. The impella has just been changed. I'm getting water out te tail tell exhaust and pee hole ect but the head seems to get very hot. I have took off the side cover to check for blockages and also done the same with the head. What is my next step. What else could it be? How how should the water be and how hot should the engine get. The warning buzzer also don't work.
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Have you change the thermostats, this will cause it to overheat while still pumping water. -
Tested the thermostat in hot water and it opens and closes as it should. I'm just stumped what to do next?Comment
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Take a look at the plugs, if the insulators are white you could be running lean which will make the motor run hot. Post photo of plugs if you can.Comment
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The plugs are black with a small coating of oil.Comment
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You haven't said how you determined it's overheating, maybe buy a cheap optical temp gauge. I've never had one read over 160F anywhere on the powerhead.Comment
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I don't know a lot about outboards as it's my first boat. I took it too a marine engineer who was doing work for me and he said it was over heating. When it's hot you can't even touch the head for more than one second. He also tested my warning buzzer and said it don't work.Comment
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What is the serial number of the motor and then give some more history, has the motor ever performed well? What motivated you to have it worked on?Comment
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It's a 1984 dt85. I brought it a few months ago, the first time I took it out it broke down. The conrod smashed a piston and got bent. It also took a chip out of the cylinder so I had to buy a secondhand engine. I took it to a shop to have the timing done which is when they told me about the over heating. So to sum it up I don't have no history on the boat what so ever! I am regretting buying it to be honest but since I have put so much money into it to get this far I feel I need to get it sorted!Comment
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Thanks for the update. Did the shop set the timing on muffs or in a test tank, did they take it out on the water? Were the plugs new when you gave them the motor and now they're black? Not sure if it's been run at speed to know if the mixture is correct, (clean carbs).Comment
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The boat has been run in a tank both at the shop and at my house. I haven't had a chance to run the boat at full speed yet due to the over heating. I would say I have ran it at half throttle and on idle. Yeah the plugs were new when I changed the motor. How Do I change the mixture?Comment
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It doesn't sound like you need to change the jetting, I had a motor that would overheat due to running lean but if your plugs are now black and oily let's move on.
It's a little backwoods but I would put the motor in the test tank, remove the thermostat and housing, start it and note how long it takes the pump to fill the powerhead (if it is). Be ready to shut it off as soon as water flows out of the head so as not to fill the pan and ingest water into the bottom carb (keep the motor trimmed all the way down) but take a look and see if any exhaust bubbles exit with the water. Since you have spares you could even install a nipple on the extra thermostat housing and attach some clear hose to see whats happening.
If you're up for it, let me know what you find.Comment
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