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Q: Why is it overheating and no heat to cabin with fan and temp high. on 1997 Mercury Sable

Original owner, 133K miles, flushed system every 50K--Engine is Overheating after 10 to 15 mins. Upper hose line to radiator shakes w/ bubbling when hot and overflow cap whistles with new & proper mix of fluid. No hot air through cabin heat with full fan and highest temp.

What I have completed: changed thermostat; flushed lines w/treatment; blew out lines to heating coil and throughout upper system. Coolant flows out reservoir & radiator drain, line to thermostat, upper lines during inline radiator flush. Can't be sure of the flow through radiator or determine what is a proper flow of coolant during engine run.

Could radiator be clogged or waterpump bad?

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cooling system bad to air lock on this engine. may have to get to a shop, have cooling system evacuated to get all air out.
Yes--have to refill the reservoir (no direct refill into readiator)after it heats and cools. May just be low fuel and air trying to get out. Thanks for all the advice.
What happens with the thermostat removed? GOOD circulation? If not then suspect water pump impellor is worn out.ANY possibility of incorrect thermostat installation?OR just defective? How are you purging the system ?
Dropped the belt and while holding the pulley was able spin the blades in the pump. They wouldn't move when I first checked them -- must have been stuck. Just purchased a new water pump. Thanks for all.
Affirm---while driving (15 min trip) AC suddenly shut off and engine began to overheat. This led to my actions.
How about the radiator cooling fans, working ok? Sounds like this may just be your problem!! Let us know what you find.
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