mercrusier 5.0 MPI heating

[td860]

I have a 2006 Azure 220 with a mercrusier 5.0 MPI. I have been having overheating problems when running at higher speeds. I have flushed the water system. but I noticed that the hoses from the water pump get hot, but the hoses to the risers remain cold. The riser remains cold. though I did not touch the risers when the motor was overheating. what could that mean?

 

[Commander_47]

Check thermostat. Also, gauge sending unit.

 

[mr 88]

Would help to have a flow chart and is it a closed cooling system or open ? As in it uses anti-freeze or it does not. You could have clogged risers , exhaust manifold , blockage in elbows , thermostat stuck shut or who knows what with the info given.