Johnson Overheat

Hi. I have a 1993 Johnson v4 140. It overheats. I put a new water pump and still overheats. Can you help?  Its okay at low speed but when I go to plane the boat it overheats. Its a looper model no thermostat. Thank you



Check the thermostats and the passages. Sometimes if they are stuck open the water passes so fast through the block that the water doesn't pick up any heat. In some instances, a gasket or seal in the center section under the exhaust adaptor can cause overheating. I had one in the past that drove me nuts until I found the offending gasket. Give some of these a try and see where it takes you next. 




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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