Operating temp for 1985 70 evinrde

[stevew]

Can anyone tell me the operating temperture range for my 70 evinrude (1985 model).
Out on the water today and we went from 55 c to 78 c. Temp would sometimes go up planning and other times go down planning. Likewise trolling.
I realise how the thermostat works, but in this case such extremes in temp and at varying times seems weird.
Is this normal
Many Thanks
Steve

[boats.net]

No should stay relatively constant. You should check your thermostats for corrosion, also varify you have a good water pressure stream.

[stevew]

To check the thermostat, are there any gaskets that will need replacing. If so Ill have to get a kit before I rip it out.
The stream is good, so I'll check the thermostat.
Can you tell me what the motor should be running at temperture wise ?
Many Thanks
Steve

[boats.net]

You will need the thermostat gasket and the head cover gasket. I believe either 165 or 195 degrees.