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Coolant system

Tiny
FRODOE45
  • MEMBER
  • 2004 PONTIAC GRAND AM
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
My car is overheating. I bleed the air out of it. Seemed to help. I thought the fans are supposed to cut on when the system reaches a certain temperature. Is that true? Fans come on when I cut A/C on though. And I replaced the thermostat and coolant temperature sending unit with 180 degree thermostat after I bled the air out of the system and I have plenty of coolant in the car. Car got to 210-220. Not good. My book said check water pump by trying to move it side to side and up and down. Seems okay. Water doesn't come out of the weep hole. I don't know. Attn. ASE MASTER6371
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Monday, April 8th, 2019 AT 1:30 AM

10 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning again,

First, you need a 195 thermostat. If you do not, it will set a 128 code for the engine not reaching operating temperature.

The radiator could be clogged with debris not allowing circulation as well.

As far as the fans, with the key on, engine off, remove the wires to the coolant sensor. The fans should come on.

Yes, it could be head gasket. A leak down test needs to be done to check that. Chemical tests are not always accurate.

Roy
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Monday, April 8th, 2019 AT 1:51 AM
Tiny
FRODOE45
  • MEMBER
  • 29 POSTS
Since then head gasket and heads along with intake gaskets replaced and 195 thermostat. Engine ran a week around 200, barely over and under. Just yesterday it got 20 degrees hotter. Doesn't seem right. Any ideas? Brent
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Tuesday, May 21st, 2019 AT 2:14 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Not too bad. Are the cooling fans working?

Is this with the AC on or off?

Roy
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Tuesday, May 21st, 2019 AT 2:24 AM
Tiny
FRODOE45
  • MEMBER
  • 29 POSTS
With AC off. The car was idling around 200. Then yesterday it jumped too 220 idling. Didn't seem right when it ran all week at or around 200 though. Was wondering. The thermostat in it before I believe was 185.
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Tuesday, May 21st, 2019 AT 2:31 AM
Tiny
FRODOE45
  • MEMBER
  • 29 POSTS
Fans do work. Car must have to get hotter than 220 to come on. I don't like that.
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Tuesday, May 21st, 2019 AT 2:33 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The system is set for turning on the fans at 218 degrees.

The thermostat should be a 195, not 185. That must be installed for the engine to run properly.

Are there any air bubbles in the cooling system?

Roy
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Tuesday, May 21st, 2019 AT 2:40 AM
Tiny
FRODOE45
  • MEMBER
  • 29 POSTS
I checked yesterday. No bubbles. Let me ask you this. If the reservoir cap is good would the pressure of radiator hoses be really tight from cooling system pressure?

I am going to check for air bubbles again.
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Tuesday, May 21st, 2019 AT 2:50 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Yes, the system should build pressure to the pressure of the cap. Most caps are 15-16 lbs.

Roy
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Tuesday, May 21st, 2019 AT 3:01 AM
Tiny
FRODOE45
  • MEMBER
  • 29 POSTS
Okay thanks. I'll be in touch.
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Tuesday, May 21st, 2019 AT 3:40 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are welcome.

Always glad to help.

Roy
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Tuesday, May 21st, 2019 AT 3:48 AM

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