2004 Merc 200hp Temp Alarm

[SILVEREEL]

I've got a 2004 Merc Saltwater Series 200hp Carbed Maybe 100 hrs on it. When I run her @3800 rpms the overheat alarm starts going off (steady beep) but if I run her at higher rpms (4000 +) no alarm. The impeller was replaced last spring and the thermostats last month. I've got good flow out of the pee hole when the alarm is going off. If I put her in neutral and rev the motor the alarm shuts off after a few secs. Any Ideas what to check? Thanks Dan

 

[achris]

Re: 2004 Merc 200hp Temp Alarm

Poppet valve....

 

[SILVEREEL]

Re: 2004 Merc 200hp Temp Alarm

Is there a way to test the poppet valves or are they something you just replace? Thank you

 

[achris]

Re: 2004 Merc 200hp Temp Alarm

If you have a water pressure gauge on the dash you'll see the opening point of the valve... If you don't have the gauge, then install one, and pull the valve apart and clean it out....

 

[SILVEREEL]

Re: 2004 Merc 200hp Temp Alarm

Just went down to the boat to try diagnosing problem and noticed the pink/blue wire labeled eng temp sensor and it runs to the sensor on port side head. Looks like the wire was touching the head at some point, the insulation on the wire is worn or burnt and copper is exposed and looks like it was making contact with the head. Do you think this might be the cause of the alarm, a possible dead ground? Thanks Dan

 

[achris]

Re: 2004 Merc 200hp Temp Alarm

Just went down to the boat to try diagnosing problem and noticed the pink/blue wire labeled eng temp sensor and it runs to the sensor on port side head. Looks like the wire was touching the head at some point, the insulation on the wire is worn or burnt and copper is exposed and looks like it was making contact with the head. Do you think this might be the cause of the alarm, a possible dead ground? Thanks Dan

That'll do it....

 

[SILVEREEL]

Re: 2004 Merc 200hp Temp Alarm

I'll fix that wire tomorrow Thanks for your help

 

[hl]

Re: 2004 Merc 200hp Temp Alarm

I had a simular problem with my xr4 but it would only rum hot at 2000 - 2800 RPMs. Running at high RPMs it would not run hot. Dirt and sand can damage the impeller even if it had recently been replaced. A pressure gauge is important.

 

[SILVEREEL]

Re: 2004 Merc 200hp Temp Alarm

I'm going to install a pressure gauge this weekend. Does anyone know the normal water pressure range for this motor (2004 200hp Merc Saltwater Series) I can't find it in any of my manuals? Thx

 

[SILVEREEL]

Re: 2004 Merc 200hp Temp Alarm

Took the boat out today and had no alarm for the entire day until I was heading back to the marina and @ 3800 rpms the alarm went off again. Going to install the water pressure gauge this weekend. Should the pressure increase or decrease when the poppet operates? And would anyone know the correct pressure for this motor? Thanks