97 cad deville northstar Keeps running extrenly hotm  Have changed water pump, thermostat,cooler fan flushed radiator.  Also fuel service required light is on car wont crank now. help

Sounds like you covered everything.
The fans come on at 220 degrees but the engine continues to get hotter ? Have you tried running the engine with the thermostat out to check for flow and blockages ?

First, you must have a properly installed thermostat that is working correctly. Second, Northstar engines are notorious for air in the cooling system after draining and refilling - keep checking the purge tank level after overheating and after the cooling system cools down. Third, make sure your cooling fans are working correctly (relay, fuse, temperature sensor) - check to make sure both are running when it overheats. If all the above is correct, the problem will probably be blockage in the system (try a flush) or your water pump itself is failing.

Try to flush and fill with new fluid to get the passageways free of sediment.

Or, try to see if the fans are coming on at the right speed at operating temperature. May require new fans/relays/wiring to fix this problem.

I have a 1997 Cadillac Deville that was overheating its Northstar engine and it required service amounting to about $700.00 or so from an auto electric shop, but afterwards it ran cooler.

Good luck on this repair.

Its likely the head gasket has failed. Look for bubbles or oil in the radiator

flush your radiator first.with the thermostat out you should see the water moving if not bad water pump.this engine needs the thermostat to function properly and either a 50/50 coolant or straight coolant so it does not boil over.also make sure your fans are coming on

I'm assuming your car has the Northstar engine?.

Strangely enough,if you remove the thermostat in the Northstar engine, it will overheat, this is because the stat is both a thermostat and a pressure valve.I can't be bothered to explain in detail how the whole cooling system works but please understand that you need to put the stat back in,(or preferably a new one).As for the cooling fans,what you described is normal for the Northstar.
Further to this, look at my profile,I have provided similar solutions for overheating problems.

Well there could be a couple of problems if you live in a hot place you should change the thermostat to a lower tempatured one so the water will circulate sooner that will help it run cooler if that doesn't do it it might need the radiator flushed.

i remember trying this. if your water pump is faulty. while the engine is off, spin the radiator blade. if it spins, then your pump is out, if it stops immediately, (it has a cluth of sorts) it's ok. also use a lower degree thermostat, like 160 degrees, then it will open sooner.

car keep running hot

if its losing water it could be a head gasket or cracked head.