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Pontiac G8 - Radiator hose pops off

upper radiator hose keeps popping off

That is not good amigo… Find out why… It is either that the clamp is ineffective, the hose is incorrect…OR your engine is being allowed to basically overheat and is blowing up that upper hose like a balloon.

You need to verify the hose and the clamp and the interface of the hose to the rad and engine… Then you need to start the engine from cold and watch it heat up. While it is running…feel the upper hose, squeeze it…do the same with the lower hose as well during warmup. It would be nice if you had a handheld IR thermometer here to monitor engine temp, upper hose temp, lower hose temp… but your hand will do in a pinch.

Keep checking the temp and the firmness of the hoses as she warms up to full temp… methinks you will find the upper hose getting hot…hotter…firm…firmer while the lower hose remains cold…until finally the upper hose gets so hot and so “blown up” with internal pressure that she pops off.

If this is the case the first thing to do is replace the thermostat in the engine. Assuming you found everything was copacetic with the hose and its clamp and its fitment. Depending on what you find with the outline above…will dictate which direction to go…if we need to go deeper.

Thats my 2 cents on the issue…

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Hopefully you will not have to go deeper. If you still have problems after @Honda_Blackbird advice you may have to have it checked for a blown head gasket. A leaking head gasket allows internal pressure from the compression from the engine to enter the cooling system. Do not let it overheat in the meantime. That would cause more damage yet.

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Yes indeed… What @tcmichnorth said…

Try replacing the pressure cap on the coolant recovery tank.

Tester

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Sure that is also another source of high pressure… but if T stat is stuck… any cap will be at its mercy as I’m sure we will all agree.