Temp Gauge not working

[torkum]

Unfortunately the new temp sensor works just fine (checked with laser thermometer). My boat didn't even have a belt until I replaced the faulty voltage regulator with the new alternator kit.

So, I checked the outdrive pump works well (disconnected hose and raw water pumps in just fine). I hear the internal coolant pumps on these 170's can fail. So my question is what type of effort and money would it take to fix - if this is indeed the issue? Any insight here is appreciated.