2003 Buick Rendezvous overheating

  • 6 CYL
  • AWD
  • 83,000 MILES
Hello im stumped 3400 engine overheating frist I replaced the thermistat. No change this is what happens. Start it up heat climbs. Alittle heat from the blower. Engine heat still climbing and max out. No heat at blower. Pressure biuldiing up. Top rad hose is cold. Bleed out the air from the bleeders. Top rad hose gets warm. Blower heat is warm. Temp gauge is good. Runs fine until shut it off and cools. Then starts all over again. I did a pressure test at 17#for 2 hrs it went down 4# no antifreeze in the oil no oil in the antifreeze that I can tell.I flushed the rad heater core and block I dont under stand how air keep getting in the system. Thank you.
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have the same problem?
Sunday, December 23rd, 2007 AT 1:40 PM

1 Reply

Have the tests done below and try bleeding it again

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.

Bleeding it

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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Sunday, December 23rd, 2007 AT 3:38 PM

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