'95 90hp Evinrude Running Hot

I'm absolutely ignorant when it comes to working on outboards so I thought I would pose this question here. I recently ran across a pretty nice boat with a '95 Evinrude 90hp on it that the owner says will crank and run fine but gets hot and alarms after a few minutes. He says in his ad he has replaced the thermostat but it did no good. I have emailed him to ask whether or not it was 'peeing' a stream. What other questions should I ask or what should I check if I go look at it? Is this likely a fairly routine situation or an indication of the need for major repairs?

Thanks.

I think you need to witness a compression test before handing over hard earned money !!

The guy just emailed me that he sold the boat. Guess that ends that. Thanks for the response! Given the state of our society I've gotten very wary of buying anything that "needs a little work" as people have just gotten so dishonest.