Hey all, here is the quick summary of my issue.
A few days ago I pulled the heater core to clean out a mouse nest. After putting it pack and starting driving to NH (from RI) I realized I had a leak in the core so I put LeakStop Copper, 2/3 of the bottle or so, in so I could finish the drive. It slowed the leak by about 90% so I decided to put the rest of the bottle in yesterday morning to hopefully stop the rest of the leak for the drive back at the end of the week. That afternoon i drove it briefly and it started overheating. Felt the top hose on the radiator and it was cold so I guessed the thermostat had been blocked up by the LeakStop. Swapped the thermostat this evening which has made no difference.
Waterpump is only about a month old so I'm hoping that's not the issue.

Thoughts? Ideas?
Thanks

 

The stop leak has likely clogged the tubes in your radiator. Been there, done that.

 

Flushed the system and I appear to be A Ok. When flushing the radiator it didn't seem to be clogged but no matter, she's fixed!
Thanks!

 

After adding the remaining stop leak, is it possible the radiator was low and when the radiator was flushed, it was filled to the proper level?

 

No, it had plenty of coolant in it, I checked as soon as it started overheating.
The radiator did overflow out the top after I had changed the thermostat. I was letting it warm up with the cap off so air could escape and it got about 2/3 of the way up the gauge before maybe half a gallon pushed back out the top.
Makes me wonder if the waterpump was somehow clogged. I can't imagine how though.