35HP mercury....is it overheating?.

[agdodge4x4]

I fired up my motor after sitting for years, and the tell tale hole sprayed water, however, after the engine got hot, water NEVER came out of the exhaust, however, the water that came out of the tell tale hole was steaming hot.

I need some help from someone that can tell me WHERE the thermostat is, and how to get to it. I rebuilt a 15 horse motor, but this one is like twice the size and its a mercury. I dont know what model it is, but it is from about 1985 or so.

any help would be much appreciated, i was hoping to take her out this weekend.