496 overheating

[Butbro]

My 496 2008 still gives alarm when I go over 30, but temp gauge does not move much..
New waterpump but same problem.
What can I check next.?

See video.

 

[alldodge]

Could use your serial number

but, your motor has a temp sender for the gauge, and a ECT (engine coolant temp) switch which tells the ECM it's hot. The ECT is item 7 in link

https://www.mercruiserparts.com/bam/subassemblydetail/43086238/28188353