Gauge in car Reads normal. But when u cut off car you can
hear it boiling in overflow. Has a new tremstate . New water
May need to have the cooling system purged from some air pockets. Also make sure the fans are working for the radiator.
Ditto on what Rowerast stated, also check the pressure cap, if it is not sealing the coolant will boil at much lower temps. You may want to consider having it checked for a blown head gasket, this could be early stage warning.
I would agree with tennisshoes. You could have a bad head gasket. I would have the coolant tested for combustion gasses.
change your rad. cap. as soon as you shut off your eng. the temp. rises and a bad cap will let it blow off into the overflow tank a head gasket dont do that. and your cap is designed to suck coolant back into the rad. as it cools. also check at the thermastat housing for a bleeder screw because some cars and trucks need to have the air bled from the system when it is filled plus some have two bleeder screws one at water pump and one at the thermastat housing.
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