2005 Nissan Sentra Car overheats and blows cold air from he

Tiny
JDAVIS81
  • MEMBER
  • 2005 NISSAN SENTRA
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 46,000 MILES
New thermostat, new water pump, radiator is clean and clear, Fluid level is good, heater blows cold air, temp gauge goes from normal to hot and back to normal quickly. Tubes leading to firewall for heater are cool. Something seems to be keeping fluid from circulating. Is there a special way to purge air from the cooling system?
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Monday, December 1st, 2008 AT 4:20 PM

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Tiny
RASMATAZ
  • MEMBER
Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.
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Monday, December 1st, 2008 AT 4:25 PM
Tiny
JDAVIS81
  • MEMBER
I purged any air out of the system, refilled coolant, ran the engine. The heater still is not workinging and the car is still overheating
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Monday, December 1st, 2008 AT 11:16 PM
Tiny
RASMATAZ
  • MEMBER
Recheck the thermostat, disconnect the heater hoses and crank engine over do you see coolant flow coming out.

Test the water pump

One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator.
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Monday, December 1st, 2008 AT 11:20 PM
Tiny
RASMATAZ
  • MEMBER
Feel across the radiator for cold spots any found radiator could be clogged up
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+1
Monday, December 1st, 2008 AT 11:22 PM
Tiny
JAMES W.
  • MEMBER
When you fill the radiator to the top and let it idle, do you get continuos bubbles out the fill cap? Please advise. You may have a bad headgasket.
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Monday, December 1st, 2008 AT 11:25 PM
Tiny
RASMATAZ
  • MEMBER
Now its time to have it:

Block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following:, Pressure test the Rad. Cap, Clogged radiator, air lock in the cooling system, Fan clutch, Radiator electrical fan, collaspe hoses, water pump
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Monday, December 1st, 2008 AT 11:28 PM

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