Pump motor overheating? What now?

I have a pump that may (or may not) be on its last legs. I need to get it fixed, but can't afford to pay my pool guy a ton of dough. (Right now, I'm contemplating his $480 estimate to replace about 3 linear feet of tile that came loose over the winter)

I have a Hayward SP3000D Superpump that is driven by an A.O. Smith UST1102 1 hp pump. When I started up the pool a couple weeks ago, the pump did not sound happy. It was louder than normal, and kinda scratchy sounding. After a day or so it settled down and went back to smooth, quiet operation.

At midday today, I noticed that the pump wasn't running. I checked the breakers, timer, etc, and everything was fine. I cycled the breakers, GFI, timer, off on switch--nothing. I was able to spin the impeller easily (breakers off, of course). No joy. About an hour later, the pump came on by itself! It ran for an hour or so, then quit. Hmmm. The pump always runs hot, and it did this same thing once last year (but never again). So I hit the pump with some water from a hose, and after cooling the pump housing for about 45 seconds, it came back on and stayed on for the rest of the day.

So I'm thinking the pump is overheating (it was 91º here today, and the pump gets direct sun). I'm wondering if the thermal switch is bad (although it does seem to work), or if the pump is wearing out and running hotter than normal (it is 7 years old).

Regardless of what's wrong, it doesn't seem too hard to fix myself--even if I have to replace the pump. I could get a new pump (same model) for around $165.

What do you think I should do?

I have a 1 HP Superpump that is in a poolhouse thus out of direct sun and I think I measured the case temperature at around 140 F. They do run hot. Mine is also 11 years old and does make a squealing sound when started cold, and I mean a little above freezing, but it quiets down. If you had shorted windings it would smoke, not run for an hour and trip the thermal cutout. If something was wrong with the starter circuit which is a separate winding, centrifugal switch, and starter capacitor, the symptoms would be obvious. It would either hum and not start or overheat fast. Is the pressure normal ?
You should make sure air flow is not blocked. Sometimes critters build homes inside the motor and that could block air flow. If you can pull the back cover off and blow out the passages with an air source and give a visual inspection that would help. If all is clear then I think you are on the right path suspecting the thermal cutout itself. They do go bad. They are a bimetal snap action switch and sometimes just get weak and trip prematurely. An easy and cheap replacement.
Check things out and get back to us.
Al

Thanks for the great input Al.

I haven't pulled the cover yet. Today was a cooler day and the pump ran perfectly. I did inspect the pump and all the vents were clear, and there was good airflow around/through the vents. Given that the pump seems to be running just fine without any of the symptoms you mention, I think it's reasonable to replace the thermal switch and see what happens.

Any idea where I could find an exploded view of this pump? My old pool company provided no documentation when they installed this motor.