How to troubleshoot a generator without really knowing what you're doing

Yawn alert for those of you who don't care about mechanical stuff.

Our Northern Lights generator, which (when it works) provides us with power for our water maker (and dive compressor) and a backup power source on cloudy days, was sick. When we started running it in the Bahamas to desalinate water, it would run for about 15 to 20 minutes and then stop. It wasn't clear whether or not it was overheating.

The mechanic looked at it and gave Matt some leads on troubleshooting it.

These are shots of the heat exchanger from our generator. Matt took apart the generator to get this piece out to see if it was blocked. He looked at it and told our mechanic that to the untrained eye, it didn't seem to be blocked. Well, after taking it to a place to have it ultrasonically cleaned, the professional there confirmed that Matt does in fact have an untrained eye when it comes to generators. He said we should buy a new heat exchanger, which we did. Although the tubes aren't really blocked, there are a number of pin holes that could be causing our issue.

Matt also took out the thermostat and boiled it to see what temperature the water reached before the thermostat opened up. It turns out that the water was getting much hotter than it should have before the thermostat opened. So we also purchased a new one of these, as well as various gaskets and switches.

We had the mechanic put everything back together because she has tools to clean everything really well beforehand (which is important). Matt observed and learned so that next time we (hopefully) can do it ourselves.

So now the generator is working. We also have the new transmission in. Unfortunately, there is an air leak somewhere in the diesel lines so the engine still needs some work. Matt is going to change a valve tomorrow to see if that is the culprit.