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Discussion Starter · #1 · (Edited)
This is a long post, but please read the whole thing as it completely explains what has happened in detail...I think if you bear with me and read the whole thing you will have a better understanding of the exact situation when this occured. thanks

So I am pretty mechanically inclined. Do most the work on my Audi A4, Subaru Outback, Jeep Grand Cherokee (timing belts, water pumps, alternators, tensioners, rollers, wheel bearings...ect)

This post is for a friend of mine who does not do much work on his own car. 2006 G6 with about 55k miles on it.

We went to a baseball game tonight and on our way there, the car started overheating. Steam was coming out from under the hood and I got out (at a stop light) and noticed that there was coolent fluid leaking from under the car. We pulled into a parking lot and the coolent was coming from the overflow hose in the coolent resivor. I glanced under the car (have not put it up on ramps yet) but I have not noticed any leaking coolent/radiator hoses. So i am guessing it is all coming from the overflow hose of coolent resivor... (will get under car tomorrow to make sure)

We pulled into a parking lot and I slowly (im not stupid) and carefully let some pressure out of the top of the coolent resivor. (i was hoping there was an air lock preventing a normal coolent flow and hoping to relieve the pressure. more coolent leaked out. we went to the baseball game. once the game was over, We temporaly refilled the coolent with water to compensate for what was lost.

we got back in the car (after it cooled for about 2 hours) and within about 5 minutes it was overheating again....

pulled over to let it cool down. drove another 5 minutes and it overheated again (temp gauge said so at least.)

waited and started driving again (only about 15 minutes back to house). this time, once we were driving, the temp actually went down...it fluctuated for the next few minutes but did not go into the red again. at this point, when driving over 25 or 30mph the temp gauge went down closer to the normal range, when slowing or idleing, the temp would rise a little again but not into the red...

So, i have been searching a little, and it looks like there might be a known problem by GM with the DexCool not being compatable with the headgaskets in this car...? could the headgaskets already be going bad with 55k miles? What else could it be? I will get under the car tomorrow to make sure there are not obvious hose, thermostat, water pump leaks...

why would it have gone from overheating to closer to normal as described above? is that a syptom of headgasket issues? could it just have been an airlock in the cooling system that was releived and now running fine?

and here is my last dumb question: it is dark outside so I can not go check. I know a radiator cap is usually the first thing to check. when i had the hood open earlier, i did not see a radiator cap, just the resivor with cap and hoses. is there a radiator cap i am overlooking?

thanks so much for dealing with the really long post and please help

p.s. not sure if it matters, but friend said before he got car it had been in some sort of accident. i do not know any details about the accident at all, but just wanted to throw it out there

ok one more thing i forgot to ask. what is the warrenty on this car? does it change if friend is not the first owner?
 

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waited and started driving again (only about 15 minutes back to house). this time, once we were driving, the temp actually went down...it fluctuated for the next few minutes but did not go into the red again. at this point, when driving over 25 or 30mph the temp gauge went down closer to the normal range, when slowing or idleing, the temp would rise a little again but not into the red...
Its this part of the story that got my attention. Check to be sure the cooling fan is turning on and off. Also be sure that blades are turning when the relay closes. Turn on the A/C, this should cause the cooling fan to run.
Good luck and please let us know whats up.
 

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ok one more thing i forgot to ask. what is the warrenty on this car? does it change if friend is not the first owner?
Most warrenties are transferable but you have to do the paper work on them. I noticed on my extended warrenty that little clause. It will cost $50 to transfer it.
 

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p.s. not sure if it matters, but friend said before he got car it had been in some sort of accident. i do not know any details about the accident at all, but just wanted to throw it out there
Was it a front-end crash? That may have damaged the radiator. Other than that from the sounds of the cooling as you go faster, i would also check to see if your fans are running.
 

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I would check and make sure the thermostat isn't hung up or closed. Might just pick one up for a few bucks and put it in. I would go along with the fan theory. Are the fans running on high when it's getting hot? There is a slow setting and a high setting for the fans. slow for AC and high for over heat.
 

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Discussion Starter · #6 ·
thanks so much for your fast replies. So, I just went out there for a few minutes and the cooling fans do not seem to be kicking on withing 5 or 10 minutes of the car warming up..... They kicked on for a sec, then went back off.....

I have to go run an errand (for the wife of course) and when i get back ill drive the car around for a few minutes and see if the cooling fans turn and stay on....

Anythougts on this?

also, where is the thermostat located on this?
(on my audi it was located behind the timing belt :( but on my subi it is located easily at the bottom of the radiator)
 

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Discussion Starter · #8 ·
ok, so I started the car, drove it around for a few miles and everything was fine, no rise in temp above normal.

One thing i though was weird is that the air conditioning would not get cold....

So i came home and let it idel for a few minutes, no change, so I left it idleing and came inside for about 15 minutes. when i just went back outside, coolent all over the ground. opened the hood and same as yesterday, coolent pouring out of the overflow hose of resivore and engine temp up in the red. Also, the air conditioning will not cool down. even with the engine overheating, the coolent fans against the radiator are not kicking on...

so the problem seems to be the radiator coolent fans not kicking on i assume...would this also keep the air conditiong from cooling down? so, what is my next step to getting the coolent fans to work properly? I checked the 2 coolent fan fuses under the hood and they seem ok....

help
 

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Yes The AC radiator is in front of the radiator. With no fans to pull cold air past the AC radiator, no cold air inside. The coldness of the air inside is about 30-40 degrees colder than the temperature your AC radiator is. If your AC radiator is 150 degrees you will blow out about the same as what is in your car already. I wouldn't let it overheat anymore. You risk blowing a head gasket or wrapping heads. I'd talk to a GM dealer to see what sensor the fans are hooked to. Sounds like a Fan relay is bad. Your book will show you which fuse block the fans are in. If I'm not mistaken, there are 2 sensors. One for dash and one for fans. So I don't think there is nothing wrong with AC.

Temp sensor


There are 2 Relays I believe one for each fan. They are combined into 1 relay
Fans


Fan Relays

 

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Discussion Starter · #10 ·
thanks for the response. I checked the fuse block under the hood acording to the owners manual and both fan fuses seem ok. Im not sure where the fan relay is as I nor friend (who's car it is) have a repair manual. Im guessing I sould get one.

If I can find the relay (anyone have any idea's where it is at?) is there a way to test it or do you just replace the relay?
 

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Discussion Starter · #11 ·
I think i found the relays in the engion compartment fuse block

28 cooling fan 1
29 cooling fan series/parallel
30 cooling fan 2

So im guessing its one of these. how do i test them? do i just replace them?

any other ideas or do you guys think im on the right track?
 

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you could bypass the relay by jumping wires and see if they kick in, but I would be careful not to short out the power input of the relay. I'd run to the parts store and buy a couple for around 10-15$ and put them in. But that's just what I would do.

Just some info. There are 3 fues blocks. One in trunk, under dash, engine.. They have diagrams on them.

 

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Discussion Starter · #13 ·
ok, ive made a little progress. the drivers side cooling fan relay (cooling fan 1) was not pushed in all the way (it had wiggled a little loose.) i pused it in and now cooling fan 1 works. cooling fan 2 still does not come on despite trying a good relay in it. there is a parallel relay between the two, but i can not try a new one there until i go to the store because there are not other relays in the car that are the same.

do you think im on the right track? i got fan 1 working. should fan 2 be working at the same time as fan 1? or are they for different purposes? im guessing its the fan parallel relay between the other 2 fan relays...
what do you guys think?

thanks so much!
 

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not to sure on that. It might just be a backup fan if it gets too hot or if the AC is on.
I believe you are correct. I believe the radiator fan has two separate fans, one larger and a smaller fan. I believe the larger fan for cooling the radiator and the other for the A/C equipment. Is the larger fan powering up? If you turn the A/C on, does the second fan turn on?
 

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Maybe this will help you out.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G106.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan S/P relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan S/P relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
 

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Maybe this will help you out.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G106.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan S/P relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan S/P relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
WHOE!:eek:

There's gotta be a flux capacitor in there some where!
 

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Discussion Starter · #18 ·
Maybe this will help you out.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block. The ground path is provided at G106.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan S/P relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan S/P relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 2 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan S/P relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
wow, thanks for the info. in both situations, it looks like both fans should be running either slow or fast, but on this car only the fan 1 (drivers side) fan is running at all...

so if both shoud be running, but only 1 is, what is my next step? would it be replacing the paraellel relay?
 

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If it ends up being a failed relay, you probably want to figure out WHY the relay failed. With that few miles, it seems kind of odd to have a relay failure. Just saying....there might be more to it. The fan could be pulling too much current through the relay, for whatever reason.
 
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