Mercruiser MAG 350 with Alpha drive running hot when pushed hard

[QBhoy]

Just catching up on this. I have a feeling you may be worrying about nothing.
When I first got the boat I worried about the temp creeping just over 170 on the gauge when running high and fast....when I got the vessel view smart craft it showed me that the gauge was not really that accurate and shows higher than actual temp.

 

[QBhoy]

When running anything other than flat out the gauge reads 150oF something but the smart craft shows 61/62oC (my uk setting on units) which is 140 something.

 

[twgroom]

Problem solved. Thanks for all the suggestions. First of all it is nice to know that my 5 year old risers are in very good shape. Problem ended up just being a faulty thermostat and most likely the scale in the thermostat housing was probably a contributor to the problem. Instead of the fluctuations in temperature that I had before, the engine now warms up to 160 and even running full out for extended periods never gets more than 165.