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2003 Pontiac Montana overheating

Tiny
ADTUCKER
  • MEMBER
  • 2003 PONTIAC MONTANA
  • 210,225 MILES
My van keeps overheating it started when my drive belt began to shred I put a new belt on the van and it was fine for awhile then it began to got hot where it progressed to completely overheating and when I turn my heat on it runs cold air I changed the thermostat and the water pump and bleed the air out it builds air up and still continues to over heat can you tell me what could cause it? Could it be low on freon? Or is it a head gasket of intake valve
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Sunday, November 17th, 2013 AT 5:32 PM

12 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
It could be a few things, plugged radiator, cooling fans not working. Let me ask you a question. You mentioned that it builds pressure. When the engine is cold, if you remove the radiator cap and start the engine, does coolant shoot out of the system?

Also, let me know if it only overheats when in stop and go traffic.
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Sunday, November 17th, 2013 AT 5:51 PM
Tiny
ADTUCKER
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  • 7 POSTS
When you first start it yes the water and the antifreeze shoot out when the radiator cap is off it overheats all the time now driving or just sitting. We can hear the cooling fans kick on. When it overheats it also doesn't leak anywhere like out of the motor if the radiator cap is on it backs into the overflow tank but that is it there is no leak onto the ground or anything
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Sunday, November 17th, 2013 AT 6:05 PM
Tiny
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When the engine is cold, the coolant should NOT shoot from the radiator when the cap is off. Since it does, that tells me that compressed air is entering the cooling system and forcing it out. That is usually the result of a bad head gasket. Have you checked to see if any of the coolant is mixing with the engine oil? Or, is any of the oil getting into the cooling system?

Let me know if what I described is happening.
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Sunday, November 17th, 2013 AT 6:15 PM
Tiny
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  • 7 POSTS
I did look in my oil there is no water and it's not a milky color either.
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Sunday, November 17th, 2013 AT 6:17 PM
Tiny
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  • 7 POSTS
And no oil comes with the water and antifreeze
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Sunday, November 17th, 2013 AT 6:20 PM
Tiny
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That's good news. At least I know none of the internal bearings have been damaged from coolant. However, I hate to say it, but I think you have a blown headgasket. If the coolant shoots out when the engine is cold, that tells me that pressure is entering the cooling system.

Are you able to do a compression test to see if there are any low cylinders?
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Sunday, November 17th, 2013 AT 6:25 PM
Tiny
ADTUCKER
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  • 7 POSTS
How do you do that
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Sunday, November 17th, 2013 AT 6:28 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Go to this site and let me know if it is something you can do. You will need a compression gauge. Most parts stores will lend or rent you one.

https://www.2carpros.com/articles/how-to-test-engine-compression

Joe
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Sunday, November 17th, 2013 AT 6:31 PM
Tiny
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Head gasket failure is that pretty common with this vehicle everything I have read says head gasket or intake valve. So head gasket for sure?
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Sunday, November 17th, 2013 AT 6:32 PM
Tiny
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  • MECHANIC
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I hate to say that I am 100% sure without being there to check it. But, based on what you told me, I am 99% sure that is what the problem is. I wish I had better news.
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Sunday, November 17th, 2013 AT 6:37 PM
Tiny
ADTUCKER
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  • 7 POSTS
It's ok thank you for your time :)
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Sunday, November 17th, 2013 AT 6:45 PM
Tiny
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Let me know what you find.
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Monday, November 18th, 2013 AT 4:53 AM

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