Temperature Guage fluxuates from 3/4 to hot (red)

Tiny
INDYRAYJ
  • MEMBER
  • 1999 CHEVROLET VENTURE
  • 3.1L
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 130,000 MILES
My van has a cooling system problem. During Idle, after my van gets up to operating temperature, my temp. Guage fluxuates between 3/4 to red hot with the warning light. Seems to only happen while @ idle. The temp. Guage goes down to almost normal but slightly fluctuates while driving at normal speed. The fans are working and it is full of antifreeze. Not sure how to bleed the air out of the system. Replaced the thermostat before winter and it had heat. The A/C however has not worked since we bought the van a couple years ago. Not sure what I need to do next. Help?
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Wednesday, May 6th, 2015 AT 12:42 PM

6 Replies

Tiny
MASON03152012
  • MEMBER
My first thought would be that there is air in the cooling system. If this van has the 3400 V6 engine it, there is going to be a bleed valve on the upper radiator hose housing, the second one is on the passenger side of the vehicle. Its on a tube that runs around the motor. Its going to be a black metal line. You want to crack the lower one first and bleed the air out. You want only a steady stream of antifreeze. Once the air is bled out of that one, crack the one higher up. Make sure there is a steady stream there also, refill radiator and overflow tank. While running and the cap is off of the radiator, check to make sure that the antifreeze is coming back out the top, the only concern I have is with it being a 3400 V6, the odds of it needing head gaskets are likely. Hope this helps you out some, let me know if there is anything else.
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Wednesday, May 6th, 2015 AT 4:36 PM
Tiny
INDYRAYJ
  • MEMBER
The van is a 3.1 liter. What is the procedure to bleed the air out of that size engine?
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Wednesday, May 6th, 2015 AT 6:58 PM
Tiny
MASON03152012
  • MEMBER
The 3.1 or 3100 vs. 3.4 or 3400 are virtually the same, the bleed out procedure should be the same. Except on the 3100 the bleeder is on the passenger side, on the top of the motor. It is on a a black metal tube, next to the power steering pump. Check to make sure coolant is full, and start the vehicle. Once it gets up to normal operating temperatures, crack that bleeder open slowly. You should have a small amount of coolant coming from bleeder. Let it bleed a few seconds then close it, and wait a couple minutes. Then crack it again and repeat this process until there is no more air in the system.
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Wednesday, May 6th, 2015 AT 7:48 PM
Tiny
INDYRAYJ
  • MEMBER
Will give that a try. Thank you sir.
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Wednesday, May 6th, 2015 AT 7:54 PM
Tiny
MASON03152012
  • MEMBER
No problem, hope it helps. Let me know if the problem is solved or if you have any further questions.
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Wednesday, May 6th, 2015 AT 7:58 PM
Tiny
HMAC300
  • EXPERT
Check radiator for cold spots if you feel any then the rad is bad. Make sure engine and fans are off or disconnected.
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Thursday, May 7th, 2015 AT 6:56 AM

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