My Boat Is Equipped With 2 Cummins Diesel Engines Model VTA 903M. What Should The Water Temperature Be Running At? The Starboard Guage Registers At 160 Degrees The Port Very Close To 200 Degrees. What Do I Need To Do To Correct This?

If the temp. Of water 160 f or 200 f it is normal condition .
To know the cause of this difference , you have the following possibilities :
- check sea water pipes is there are obstacles .
- check the cooler and clean it .
- check the thermostat .
- check if the there is black smoke ( uncomplete combustion ) .