OMC 5.8L engine overheat but guage says 190

[cheers731]

My 92 Four Winns with 5.8L Cobra overheated yesterday. It has a close cooling system and the heat exchanger feels very hot and the big hose from engine water circulating pump feels hot too. All other hoses are cold, not even warm. The temperature guage said 180-190 but engine suffer no power, eventually can only run at idle speed. I did a search on the forum and one post has experience the same thing that a 5.8L engine overheat but temperature guage shows 190. Two risers are lightly warm by hand touch. Some grinding noise came from engine water circulating pump area once a while but always stopped. I didn't notice water near it.
Do I have a engine water circulating pump failure or something else, and I will appreciate very much if someone can provide me the replacement part number for it.
Thanks

 

[Bondo]

Re: OMC 5.8L engine overheat but guage says 190

Ayuh,... So how old is the raw water pump impeller,..??

 

[cheers731]

Re: OMC 5.8L engine overheat but guage says 190

By the way, when I was examing around and notice a label saying zinc anode in heat exchanger needs to be replaced yearly. I have never done that. What is it?

 

[cheers731]

Re: OMC 5.8L engine overheat but guage says 190

Not sure, I bought this boat 2 years ago. I assume if the impeller has gone bad, the riser will be hot too. It was barely warm when it was running at 3500 rpm.