1984 115 V4 water problem

I just had a baffling thing happen to me. I replaced the powerhead with a reman from Outboard Recycle, put new thermostats in, new water pump kit. I went through the break in procedure, and the last step, I had an oddity occur. The hot horn started sounding, so I shut the motor down. This was at idle speed. I had one head getting hot (port side), which was the source of the hot horn. So I let it cool down, and luckily the wind was in my favor, blowing the boat back toward where I'd come from..... The hot horn stopped, so I restarted the motor to see if it would happen again, which it didn't....My first thought was thermostat or poppet valve..... So I took the boat back out, and it performed flawlessly. Fast forward to today.....I launched the boat, started the motor, and ran it to the courtesy dock. Water was flowing at a rate of 7PSI at roughly fast idle, 5.5 at idle. So I went and parked my vehicle, came back to the boat, started the motor, and got NOTHING!!! No overboard stream, no pressure on the water pressure gauge. Now knowing what I just went through the other day, I'm still thinking thermostats, even though that makes absolutely no sense since it should pee before thermostat activity. Has anyone burned up a water pump in the water???? This blows my mind. The motor was NEVER started out of the water. Do you think the key sheared, and how? It's one of the plastic wedge type keys. Or is there something else I should be looking at?

did pump kit come with 2 different keys,2different sizes.wrong size one and key could slide out

Yes, it did. I put the bigger of the two keys in, and it sheared off. Never had one do that before! So THAT problem is solved....So I went and got another key, but have another problem. One head consistently gets hotter than the other. It seems to me to be thermostats, but those have been replaced when the powerhead was done. One thing I did notice, the water pressure on the gauge is inconsistent. At idle, it will read 5lbs of pressure. Then, the starboard head was the hot one this time. I had the port side heat up the last time. I'm lost as to why it's doing this. So I pulled the hoses, started the motor, and had great water flow from those hose at that time. Hook the hoses back up to the thermostat housing, and it heats up again. What temp are these thermostats supposed to open? I pulled them and checked them, and they both opened around 155 degrees, which to me, seemed almost too hot as the book calls for a max temp of 163 degrees. Think I have bunk thermostats? I can't seem to locate anything in the book about testing the opening of the things. Another thing, they don't open fully until the temp on the pan of water is over 170 degrees. That seems awfully hot for them to be fully open if the hot horn will sound at 180 degrees. These are the Seirra branded thermostats.

On v4s&v6s for some reason one side usually runs hotter than the other.My friends 225 runs 20 hotter on starbord than port.nature of the beast. Do u know the specs on the stats that were installed. they should be 143s,im not sure, thosestats dont open up much more than three eights-half inch.170-180 is too hot.I would look for cooler stats. A heat gun would come in handy,If you can keep your bare hand on a head for a six second count without burning your skin your ok

You are installing them correctly???