1999 Chrysler 300 overheating

1999 CHRYSLER 300
147,000 MILES • 6 CYL • FWD • AUTOMATIC
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LTJ123
  • MEMBER
  • 1 POST
new heads installed had bent valves entire cooling system is new pump,t-stat,radiator,temp sensor,fans. car runs great and at idle doesnt over heat at cruise speeds the engine rapidly over heats , cooling fans come on around 210 deg. and stay on at idle performed block test and checked ok i can see the coolant flowing in the bottle upper hose hot lower hose cool to touch heater works great both hoses to core hot .put a second thermostat thinking possibly was bad and used a vacufill twice to install coolant thinking maybe had an air pocket timming seems ok and no check engine light. any ideas would be great thanks
lee
Mar 11, 2010 at 10:51 AM
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HMAC300
  • ✓Experienced Mechanic
  • 48,601 POSTS
check for blockage at front of radiator. If you have one of those "bug screens" throw it away it blocks 15% of air flow. If the top hose is hot and bottom cool that is the way it should be . And what do you call overheat? is the needle going all the way into red or just on the high side. And what is the actual temperature when overheating? Has this been checked mechanically, you could always have a bad ground causeing your gauge to go screwy. everything you say has been replaced, but how about the cap? it's one of the weak points on a rad system if it has one. If you have an air pocket that may cause it but it should have worked out if cap was ok. Only other thingi can really think of without seeing the car is maybe a head gasket on wrong. good luck
Mar 11, 2010 at 12:27 PM
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