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Cooling problem with my 150 efi v6... one side of the engine…

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Cooling problem with my...

Cooling problem with my 150 efi v6... one side of the engine cools the other side ( starboard) gets hot and the alarm will sound.... impeller , waterpump, EVERYTHING is replaced...HELP!!!!

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Power loss after driving for two minutes...overheat alarm will sound and the cooling water is real hot... engine was completely taken apart and flushed....new impeller, waterpump, housing brackets etc... now one engine side stays cool, the other side still gets hot...

Submitted: 7 months ago.Category: Boat
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11/29/2017
Marine Mechanic: Jason, Marine Mechanic replied 7 months ago
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 17,845
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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Hello my name is ***** ***** am I speaking with? I read what you wrote but I do not see any kind of model information. Who makes this engine. Do you have a year/make/model or serial number on it?

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Customer reply replied 7 months ago
Hello this is mike.. i am on Bonaire ..in the caribbean.. i have a mercury 150 efi 2.5 v6 2006 model...
Marine Mechanic: Jason, Marine Mechanic replied 7 months ago

H​I Mike. Okay got it. Is there any story or history to this outboard, have you ever personally seen it cool correctly? How many hours on the outboard? Are you near it now for a couple of tests?

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Customer reply replied 7 months ago
it is in a boatyard right now with a .. mechanic,, it has about 200 hours and was running perfectly untill suddenly the overheat alarm went off.... like i explained ... the whole engine was taken apart and parts where changed.. now one side is cooling well , the other side stays hot... any suggestions? he is trying to flush it now with acid ....
Marine Mechanic: Jason, Marine Mechanic replied 7 months ago

Definitely not acid, not unless somebody is looking to die. Acid + aluminum makes for toxic gas that will kill. The only thing I would want to know is this. If you pull the thermostats out, leave the covers off and leave the holes for the thermostat open. Then either hook up the flushing muffs or put the outboard in the water. Start the engine up. Is there water flow out of both thermostat holes or is there only water flow out of 1 thermostat hole. That would be what I would need to know.

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Customer reply replied 7 months ago
when you flush it it comes out of the two holes... it runs much better then it did but still one side is way to hot according my,, guy,,
Marine Mechanic: Jason, Marine Mechanic replied 7 months ago

What two holes are you talking about?

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Customer reply replied 7 months ago
i thought we were talking about the thermostat holes..
Marine Mechanic: Jason, Marine Mechanic replied 7 months ago

Okay so have you already done this test, running the engine with both thermostats out and the holes exposed?

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Marine Mechanic: Jason, Marine Mechanic replied 7 months ago

Okay next, put everything back together. Start and run the engine, and take the temperatures of both cylinder heads with an infra red temperature gun. What is the actual temperature of each cylinder head reading when the alarm goes off?

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