overheating issue

[mreider]

I recently replaced the thermostate in my 125hp Mariner outboard thinking it was the reason for getting the overheating alarm after operating for a short length of time at WOT. Still have problem and was told that it could be an obstruction. What does it entail to check for this and what is a fair price to pay?

 

[galamb]

Yes, it could be an obstruction or bad impeller or rotted water tube, bad gasket somewhere or it could even be simply a bad temperature sensor (which is a common issue).

If you are looking at have a shop check they will generally charge you an hour to troubleshoot. They will run the engine and check the temp when the alarm goes off to try and determine if it is in fact overheating or the sensor is bad.

The sensor can be tested. Also the water channels can be blown out if there is an obstruction.

So figure on an hour to diagnose and then depending on the exact issue, the parts/labour costs will go on from there.