2007 Pontiac G6 Coolant Leak and No Heat

Question: Low coolant level warning problem with my 2007 Pontiac G6 3.5L V6. I Added antifreeze several times. My 2007 Pontiac G6 with the 3.5L v6 engine is loosing anti-freeze. We have added several times, but gets low after driving a few weeks. When it goes low, the heater wont blow warm air when sitting at an idle.

We have taken it to a shop 2 times. They pressure test, but cannot find a leak, although we smell it from time to time. What can I do to repair this problem?

Answer: The first thing would be to have a cooling pressure system test done to see why you are low on coolant. Low coolant will cause air pockets, and that is the most likely cause of no heat in the car, as long as the engine temp. is up to normal. Some common areas are of course water pump, hoses, coolant pipes.

There is a technical service bulletin on this car for no heat at idle. There is a procedure to remove air pockets that could be done. The problem with this bulletin, is where did the coolant go to begin with. We have seen  several of the 3.5l, and 3.9 V6 engine have leaking head gaskets causing this condition. There are a few other places that are common for them to leak. As with any vehicle, the water pump is common. Also, on the front of the engine is what is called the "Coolant crossover manifold" This aluminum manifold connects the front and rear cylinder heads. A little hard to determine if these gaskets are leaking. You will need a pressure tester and a good eye.

G6 Coolant Temp Sensor Location

2006 Pontiac G6
Engine Size : 4 liter
Question: where is the engine coolant temperature sensor located at?


Answer: Well, first of all there is no 4.0 L engine in a 2006 Pontiac G6. Assuming you have the 3.9L, then the coolant temperature sensor is located on the drivers side of the front cylinder head, just above the transmission.

1997 Pontiac Bonneville 6 cylinder.

Question: Driving down the road the heater will be on blowing warm air, the display on the dash will start flashing and the air turns cold instantly. Thermostat was already changed. What could be causing this. Not leaking any fluid. Fluid level is good.

Answer: The control head flashing is usually a sign of an electrical problem in the control head, not an engine problem. This may be malfunctioning and causing the temperature door in the dash to switch to cold. I believe this model also has what is called a "Heater A/C Programmer" which also controls the temp and mode doors. Would need to be checked out with a mechanic and a schematic to pinpoint the problem.

Pontiac G6 Oil Leak

Question: What is causing an oil leak on my Pontiac g6? The oil is dripping off the bottom of my starter and a drip from above my starter.

Answer: Sounds like the oil pressure sending unit is leaking. This is above the starter.

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Comments (10)
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  • Guest - FRANK

    in ideas guys

  • In reply to: Guest - FRANK

    OK, then check all the fuses.

  • Guest - FRANK

    ok but dont have no power to the control panel on lite come on the control panel like its a bad fuse

  • Guest - FRANK

    no power to control panel or blower motor,blower motorer was replaced

  • In reply to: Guest - FRANK

    A bad blower motor would not cause a no power condition to the control panel, so not sure why you replaced it. Be sue to check all fuses. If OK, then you would have to do some diagnosis for power and ground to the control panel.

  • Guest - Bob

    Most likely the rear head gasket is blown. Also check the coolant crossover as stated above. The coolant will evaporate before you ever see it on the ground if it is an external leak. The heads don't crack too often, unless it overheated really bad.

  • Guest - Mike

    We have a Malibu Maxx 2007. It is losing coolant, no leak can be found. Had it pressure tested, no leak found. Mechanic just told me they are seeing problem with a head cracking and then the coolant goes out the tailpipe leaving you low. We went low had no heat, added coolant. 2 months later over heated, added more coolant. Not a drop on the floor, until it over heats and then she blows out what is left. He told me about 1200 to fix. 450 for the head and a whole bunch of labor.

  • Guest - k dogging

    Anyone with a G6 3.5l with a coolant leak? Change your water pump. l'll guarantee problem solved. You can get a pump for around 70 bucks. I'd suggest changing the serpentine belt too as it will be saturated in coolant.I did mine and it worked perfectly.

  • Guest - Troy

    I had the same problem on my 2006 Chevy Impala. When you're sitting at a stop light, you can feel the heater start to get cooler and cooler. Took it to the Chevy dealer and they said the anti-freeze was low. Something about a coolant crossover gasket and the back cylinder head gasket. It was a pretty big job to replace those parts. It took all day. I did not get my car back until the next day. The total cost for that repair was $1300. Too bad my Impala wasn't a 2007 model year, because then it would've been covered under the hundred thousand mile powertrain warranty.

  • Guest - k dogg

    In reply to: Guest - Troy

    You got ripped off. It was your water pump, which they also replaced, but it's so cheap they take the loss. They just say it's your gaskets because it's more expensive, even under warranty, because they get more for the bigger job. So your gaskets were most likely not touched and I'll bet they replaced your water pump, which was probably the problem and a do-it-yourself fix for the mechanically inclined.