Hi temp alarm comes...Johnson motor

Hello this website is great! I just ordered some parts. My questions the following...I have a Johnson SLP 28<br /> Model=J28ESLCUC<br />SN=E6259720<br /><br />The hi temp alarm comes on after about 10 minutes at idle around 1000RPM sometimes....not all the time...or like today I was anchored in a channel for about 10 minutes..engine was off went to restart and after about 5 minutes the alarm came on around 1000RPMs again. I made my way back to my dock running at 3000RPMs thinking that would make the audible alarm go off, but it didn't though it did changes tones...what is the solution?...for now I cut the wire to the horn....I see a nice stream of water coming out of the motor at all times so my water is working or maybe not?<br /><br />How to I stop the audible alarm?...I am running the motor in a freshwater lake in IL.

Re: Hi temp alarm comes...Johnson motor

Hello Ben and welcome to iboats.<br /><br />First...when th alarm goes off, you got a problem. Don't solve it by disconnecting the alarm horn. That's a good way to destroy your engine.<br /><br />From your post, it is most likely you need to change out the water pump impeller. What happens is, the "fins" on the pump impeller get bent and won't spring out against the pump cup. The impeller is made of rubber. At low speeds, the pump can't pump enough water to keep the engine cool. You have to get more rpms to supply enough water.<br /><br />Replace the impeller. And while your at it, replace the t-stat. Your problem should go away. <br /><br />Keep us posted......thanks.

Re: Hi temp alarm comes...Johnson motor

Thanks for the quick repsonse.