[gdisselkamp1]

So i was looking at the overflow pressure tank in the 05 equinox that i just bought and it looked kinda dingy inside. So i went to go take the cap off cause i wanted to see how dirty the coolant was and kaboom the cap blew off like it had 100 psi behind it. Wel because antifreeze exploded everywhere the check engine light came on probably because coolant got on the coils or spark plugs and of course it was spitting and sputtering. So we drove it for a little bit then decided to take it to the dealership because of the check engine light. Well wouldnt you know on the way there it was driving fine and then as soon as we pull into the dealership the check engine light goes away. So obviously the coolant had evaporated and there was no other problems other then the psi in the pressure tank being way to high. oK SO NOW TO MY REAL PROBLEM! Why is this overflow pressure tank psi so high. Well ok so the dealership did the hydrocarbon test on the cooling system and found that in fact exhaust gases were getting into the coolant system. But there are no symptoms of a blown head gasket. The engine temp stays very steady and there is no big cloud of white smoke behind me and other then the fact of the coolant on the coils the car drives very nice. So i would like anyones opinion on if you really think this car needs a head gasket a week after i bought it. Has anyone else experienced high pressure in this tank. The car did sit for about a half an hour before i opened the tank. Although the coolant that did spray all over me and my fiancee was pretty warm. So does anyone think the pressure was so high just because it was not cool enough? I have heard that the hydrocarbon tests are kinda hear and there. Any help would be appreciated.

 

[Steve A]

Usually if you have a blown head gasket you can see bubbles in the overflow tank.

When cold, take the lid/cap off the overflow tank (make sure it is about half full - or at the proper fill mark) then start the engine and let it run for awhile. If you see bubbles appearing in the tank you have some sort of leak of combustion gases. This will normally be a head gasket, but, in rare instances can be a crack, or poor casting, in a head that will allow gas to escape into the cooling system. Being a new vehicle, it could be either, while on an older vehicle it will usually be a head gasket.

There should be some way for excess pressure to escape from the overflow tank that is created when the engine/coolant gets up to normal operating pressure and the coolant expands. Usually it is some sort of spring loaded apparatus in the lid/cap of the tank. This could possibly cause the problem of excess pressure you experienced. I'd really check this possibility out first if it were my problem.

 

[gdisselkamp1]

So does anybody think that i need a new headgasket with the results of the hydrocarbon test being positive? Ive gotten another opinion from a different shop and they seem to think it doesnt need a new head gasket because there are no symptoms. for example overheating, varying collant temp, leaks or cloud of white smoke out of the back. Could i have have a bad or going bad head gasket without these symptoms?

 

[Steve A]

You are correct, I overlooked - or forgot - that little tidbit. :-[

Odds are, if there is a leak, it will be a headgasket. But, do the test I outlined about the bubbles.

 

[redlight_005]

As Steve A said, you could first try changing your radiator cap.

 

[creeper514]

Hi, well i also have same problem. I own a 2011 4cyl awd Lt. Just the other day me and my brother were looking at car and why so much pressure build up. The fluid level was to correct mark. We came to idea that it getting forced pressure from motor. Well top it off. I drove home that afternoon and parked car. Went got ready to go out. Started car and it ran terriable. Stumbling,bucing,like running ojt off gas and gauges going crazy. Well i looked in mirror and had cloud of white smoke pouring out exhaust. I shut car off opened hood. Well my coolant resevior was bone dry. Took cap off and omg the pressure that came out was amazing. But no fluid. It got sucked into motor. Checked my oil to see if it going into it. It wasnt. So my headgasket blew and is flooding my cylinders. The real sad thing is this is a brand new motor with only 3600 miles on it. I had it replaced because old motor was burning up oil. So now i have to havd them fix this again and i want another new motor. It under warrenty still. Im really dissapointed in American made products. I kick myself getting rid of my jeep and dealing with this now.

 

[Terrainguy1978]

Im really dissapointed in American made products. I kick myself getting rid of my jeep and dealing with this now.

Just an FYI...a Jeep is made by Chrysler...American made. Also, you go on any forum for any car manufacturer and you will see complaints about them all... be it a Toyota, be it a Ford, be it a GM. All car manufacturers have cars with bugs, and it sounds like you're one of the unfortunate ones... however it sounds to me that GM has and is doing whatever they can to rectify the issues. If this problem has occurred on a brand new motor, then it sounds to me that it could have possibly been an issue on the technician's side during installation, I know if I ever had an issue which called for a motor to be replaced, after the replacement I would constantly be looking under the hood for leaks, checking fluid levels, etc. for the first little while to avoid things getting to the state of needing replacement again. The first misconception that people have is that just because it's new, they don't have to check things... new things break too...as you have proved with your unfortunate situation. Sorry to hear of your unfortunate experience- yes it's inconvenient and a pain in the @ss, however with patience I'm sure all will work out well.

 

[Chevrolet Customer Svc]

Hello creeper514,

I apologize for the frustration your vehicle has caused you. If there is anything we can do to help with this situation, please let us know. We are available by PM if you require any additional assistance.

Amber N.
GMC Customer Care

 

[TheBlueTonicPlague]

I have a 2005 Chevrolet Equinox LT AWD I've replaced brand new, water pump, thermostat 2x, engine temperature coolant sensor and a couple of radiator hoses. And it still gets overheated, theres no smoke coming from the exhaust and the oil isn't milky looking and no loud or somewhat loud engine noises, so I just parked it until I get answers or just get rid of it for something different. But I would love to keep this vehicle. Can anyone recommend a place that'll not just ask a bunch of questions to me and fix it, from Southern Ohio?

 

[Colt Hero]

@TheBlueTonicPlague : have you purged all the air out of the system? If not, that can make the gauge needle swing wildly. Not sure on that vehicle, but my ‘02 Impala has a bleed screw near the thermostat. It’s soft metal, so be careful. Open it to purge the air until fluid starts coming out, then close - but do not over tighten. Just enough to close it.

Sometimes the thermostat can matter, too. Did you put an OEM (GM) ACDelco unit in? I would say this is less likely the problem, but I’ve heard of off-brand thermostats causing troubles.

Do you know that the tiny tubes inside your radiator aren’t blocked??? I’ve never used any of those “magic potions” like “Stop Leak” because I think they’re just desperation products, but maybe someone poured that stuff into your radiator at some point?

Maybe try isolating the radiator and flushing/cleaning (or even replacing) it?

Do the fans turn ON when the temperature rises past normal (typically just before mid-scale)?

Some things to check ... also that you have enough 50/50 mix fluid in there ... probably takes about 11 quarts, but check your Owner’s Manual.