1989 Mariner II 150 overheating

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srawding01

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May 15, 2012
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Just had impeller and thermastats changed and motor overheats as soon as I go above idle. Tell tale is working at idle but then Steam comes out of tell-tale and alarm goes off. Could this be poppet valve? Any other ideas? Thanks
 
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srawding01

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Re: 1989 Mariner II 150 overheating

ok so I changed the poppet valve tried it and it was slower to overheat but still overheated. I live 5 mins from lake so got home took off head and gasket and saw no water was completely dry. I assume there must be a clog somewhere just not sure how or where to unclog.
 
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minuteman62-64

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Re: 1989 Mariner II 150 overheating

Maybe my dumb-*** mistake applies here. Is your water intake staying submerged when you go up on a plane? I had my motor (a 30HP '82 Mariner) off my boat for service. The mechanic must have changed the tilt-pin setting while he had it on the stand (or maybe I did while re-installing it). I didn't notice, and after I installed the motor and took the boat out I had serious overheating problems. After checking every possible source of the problem and banging my head on the side of the boat for about a week, I stood back and looked at the motor tilt angle - set two notches too low - result that when up on a plane it was bow down and stern up to the point where the water intake came right up out of the water. Duhhhh!
 
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CharlieB

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Re: 1989 Mariner II 150 overheating

srawding01 said:
.................. took off head and gasket and saw no water was completely dry...............................
Click to expand...

As soon as you shut off the motor it drains out so you will never find the block filled with water when you pull the heads.

While you have the heads off, take a very close look at the old head gaskets to see if they have been leaking combustion gases into the water jacket, displacing water and causing your over heating.

Often the leak will not show during a compression test or at low speeds and low loads, but as speed and load increases, so does cyl pressure, once that pressure overcomes the gasket seal then it starts displacing water in the cooling system and you see steam from the P stream.

Check the block and heads for flatness so the new head gaskets have good surfaces to seal against, Follow the torque pattern and settings when tightening the headbolts.
 
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srawding01

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Re: 1989 Mariner II 150 overheating

The head gaskets have been changed a week ago thats why I took the head off again to see if they had any burnt marks on them from leaking but they were perfect. I used the torque pattern when installing them. I also checked the engine angle and it has not been adjusted. It seems as though no water is getting into the water jacket. Is there any test to see if there is a blockage?
 
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CharlieB

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Re: 1989 Mariner II 150 overheating

A quick check of water flow is to remove one stat and leave the cover off, fire the motor, water should come out. Replace that stat and cover and repeat on the other side. This will simply show you how quickly the block fills.

Double check that the timing lever is moving freely to its stop when the throttle is moved to WOT. If the timing lever sticks anywhere the timing will be retarded causing overheating.

Also verify that WOT timing is correct.
 
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srawding01

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May 15, 2012
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Re: 1989 Mariner II 150 overheating

Thanks to everyones help finally fixed my overheat issue. After I tried all things decided to take off lower unit to try and flush out with high pressure to see if there was a clog. The water pipe itself was bent on end, not closed off so some water was getting bye but i guess not enough to cool properly. Also the plastic fitting that is attached to the copper pipe was also broken and clogging the pipe. Changed pipe and parts and tried it out yesterday. Runs great again. Thanks for all the help.
 
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