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GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 2006 Grand Prix that recently began overheating, losing

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I have a 2006 Grand Prix that recently began overheating, losing coolant somewhere but can't see or find a leak. Any Assistance would be great

Welcome to Just Answer and thank you for asking your question. I look forward to helping you fix your vehicle.




I will try my best to help you and in order to do that, I need you to describe the issue in as much detail because I only know as much about your vehicle as you have told me in your post, so my answer will be based on what you have posted. Please include all the small details that may seem insignificant such as warning light, codes that you have scanned and how this started. I will also try my hardest to help you avoid a dealer or shop, but with the modern vehicles an electronics, there may come a point that we cannot avoid this, and if that is the case, I will tell this.


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Please feel free to reply as needed.


I will need either the engine size or the VIN.

Customer: replied 7 years ago.
Thank you, XXXXX XXXXX is 2G2wp552861259690. I think the engine is 3.6 but I am not sure. The problem started about 2 months ago with the car overheating. After checking, it was discovered that the coolant was low. I had everything topped off at my oil change about 2 months prior to that. I replaced the coolant and within 2 weeks it began overheating again, once again, I replaced the coolant. It has been about a month since then and last night it overheated again. I can't find a leak, there is no puddle of coolant anywhere so I am trying to figure out where it is going and what the cause may be without going to a dealer because I currently do not have a job and I won't be able to find one without my car. Please let me know if further information is needed.
Thank you.
Lori Babler
OK, you have a 3.8L engine. When does it overheat, idling, driving, AC on or off?
Customer: replied 7 years ago.
all different times and not always. When I have to sit in traffic, it starts getting hot, as I speed up it seems to cool down and AC on or Off, it still does it, but I think I notice it more when the AC is on. Which is usually always,however I have been turning it off at the times when it starts overheating to see if it makes a difference and it doesn't seem to. It seems the longer the drive the hotter it gets. Like when it has been running for extended lenghths of time.
Ok, can you hear the fan running at all when the AC is on? Is the check engine light on?
Customer: replied 7 years ago.
I do believe that the fan is running when it is on but to be honest it is so quiet that I have never noticed it. The check engine light has not come on and when it overheated last night the coolant/water looked rusty.
Ok, this could be one of three things from what I can gather through our conversation. First is there is something physically blocking the airflow over the radiator. This may be easily fixed. The second is a bad thermostat. The third is head gaskets.
Customer: replied 7 years ago.
Airflow over the radiator? Can you please give me examples of this so I know what to look for? Also, any idea on the cost of a new thermastat and where I can get free information on replacing one?

Thank you

You are looking for anything that is blocking flow to the rad, if the fins are bent, some trash or debris blocking it. The thermostat is cheap, 25 or so and there are no free options for information, but as part of this I will post the instructions.

J 38185 Hose Clamp Pliers

Removal Procedure

    Object Number: 308970  Size: SH

  1. Remove the fuel injector sight shield.
  2. Partially drain the cooling system.Use the J 38185 in order to reposition the hose clamp from the water outlet housing.
  3. Remove the radiator inlet hose from the water outlet housing.
    Object Number: 153572  Size: SH

  4. Reposition the wiring harness from the water outlet housing stud.
  5. Remove the water outlet housing bolt and the stud.
  6. Remove the water outlet housing and the gasket.
  7. Remove the thermostat.
  8. Clean and Inspect the water outlet housing gasket mating surfaces.

Installation Procedure

    Object Number: 153572  Size: SH

  1. Install the thermostat.
  2. Install the gasket and the water outlet housing.

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the water outlet housing bolt and the stud to the water outlet housing.

    Tighten the bolt and the stud to 27 N·m (20 lb ft).

  4. Install the wiring harness to the water outlet housing stud.
    Object Number: 308970  Size: SH

  5. Install the radiator inlet hose to the water outlet housing.
  6. Use the J 38185 in order to reposition and install the hose clamp to the water outlet housing.
  7. Fill the cooling system.
  8. Install the fuel injector sight shield.
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