DF25 overheating? Over reviving?

[Russell]

I have a DF25 4 stroke. It starts up and idles fine, and it runs good up to about 1/2 throttle. If I go above 1/2 throttle an alarm sounds and the motor drops down to idle speed. It usually take about a minute for the alarm to come on, so I thought it was an overheating problem. I’ve changed the impeller and cleaned out the cooling system and yesterday I changed the thermostat, it still does the same thing. The “pee” stream is nice and strong, and the oil level is Good also, so I no longer think it is cooling. I’ve read forums about over revving and am not sure that’s what is going on. The only way to reset the alarm is to put it in neutral and turn the engine off for about 30 seconds. I hope someone has an answer for me, this has been going on for over a year now. Thank you, any suggestions will be greatly appreciated.

[Hoosmatroos]

Do you have any more info on the motor? What year/model? Did you guess it could be a temp problem?

[Russell]

Hi, the motor is a 2007 DF25 4 stroke v- twin. Yes I guessed it was overheating due to the motor working harder and the alarm would sound. The impeller did need changing, so I’m glad I changed that.

[Hoosmatroos]

To be sure you can use a infrared temp gun to check what temp your motor is when the alarm sounds. It can still be a temp problem and this way you can rule that out

[Russell]

I will have to check that this weekend. Do you know what is normal operating temperature?

[Hoosmatroos]

I think the max should around 75 C. Not much higher. Thermostat fully opens around 68 C. Don't precisely know when the alarm should go off

[Carold]

This sounds like the same thing that is happening to mine, I have been told by a mechanic that the head is cracked..... looking for feed back, I have also been told by another that that happening to a 115 is rare.