1971 pontiac grand prix

Check coolant level, radiator fans, fans relay, thermostat. If check engine light is on, pull code(s).

If your driving a 71 GP you probably have a good idea on the basics but here's where I would start. Check antifreeze- needs to be full and fresh, try one if those mini turkey baster with the 5 balls, not precision but it'll let you know for a few bucks. Thermostat- pull it and replace housing, remove the cap and start. Antifreeze should be visibly flowing in radiator, if not you might have blockage. On my 78 was a valve that only let warm af into the heater core located under hood by the firewall, make sure it's not clogged or installed backwards. Check your fan belt and water pump pulley and make sure your water pump is turning. If pulley is turning doesn't mean the water pump is moving af. I didn't always have a thermostat installed in my old 70s V8s. The heater wouldn't get as hot and if you have a leak try a pressure release cap with red lever up so it won't build pressure but with therm out af can still flow, if water pump is working. Not good for long-term or extreme driving. A better idea unless you have oily af or excess milky oil~damage to head, head gasket, or block in which case DONT JUnK IT. If you don't care to go that far, somebody will, not running your sitting on more than chump change, try a flush and fill with a new thermostat. Use proper antifreeze and distilled water, or 50/50 pre mix. No Dex cool, that crap will gunk any motor up if mixed wrong or left too long! A clogged heater core can affect the system also. Or it might be as easy as a worn or loose fan belt. The belts are adjustable, to a point. Good luck and before calling it quits find someone who won't, take the money and find one that's better running. Quick guesstimate for everything I've mentioned(except heads and block, or maybe radiator) under 200$ (not counting labor)! There might be more but that's what i remember, and this reply will start getting boring if I don't shut up. FYI- put sealant on housing, valve cover, etc., with finger apply thin film of motor oil to mounting surface and your set to remove and replace repeatedly, oil surface each time you replace. Can be helpful with rubber gaskets also!!

Jorge_ if you can pull codes from a 71 Pontiac many diy'ers including self should be kneeling at your feet. Please, do tell, further explanation is highly anticipated?