04-25-2018 07:53 - edited 04-25-2018 07:54
A number of things can cause an overheat condition besides just a waterpump. Have a trained tech do the factory troubleshooting procedures to find and correct the problem. Often thermostats, debris in the system, or a pressure relief valve could contribute to temperature fluctuations.
If you plan on doing it yourself, please refer to a proper factory service manual and latest service literature and read the disclaimer at the bottom of this post.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.