My 2005 Vibe was overheating due to leak. I put in some stop leak and it worked ok for a couple months then started overheating again. Since it seemed to be leaking again, I decided to replace radiator, water pump and thermostat. Now car runs mostly ok, but if I go up a long hill and stress the engine hard, the heat gauge will creep up. It I stop at a light and idle the car it will cool down pretty quickly to normal range. There is no oil getting into coolant or coolant into oil. Not sure what is going on here. Please help!
It is possible that the stop leak restricted some of the cooling passages inside the engine slowing the flow, so under higher than normal stress the flow is not enough and it starts showing too hot. Have you tried reverse flushing the block, sometimes this will dislodge the restriction but not always, in worst case you will have to disassemble the engine and have it hot tanked to clean it all out, but hope it doesn't come to that. Stop leak is one of the worst things ever for automotive use, it was designed for big rigs with massive cooling systems as a temporary solution for a leak in a massive radiator until it could be resoldered or the damaged tube removed and replaced.
Miracle in a can isn't. lesson for everyone.
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