Major cooling problem, maybe bad headgasket??

[Rogue Leader]

Hey guys, LONG time no speak. Let me give you some history as I'm freaking right now at the possibility I need to rebuild something in the top of my motor.

Before we start at no point has the car ever overheated during any of these scenarios.

2010 SS M6 72k miles. At 55k miles 3 years ago I had a collapsed valvespring, car was towed to dealer and top end parts replaced, drivers side headgasket replaced etc. Got the car back it was perfect. 1 year later the drives side catalytic converter failed (due to last years valve spring problem most likely) while being replaced I had coolant flushed. Car is great. Fast forward to last year radiator blows. I swap radiator out, fill up with coolant, burp the system (or so I think). Car is rarely driven until march of this year about 500 miles later and I am parked on a slope nose down and notice coolant leaking from overflow tank. I think its cracked so I replace it, Refill and go. Leak returns, I realize that I have overfilled coolant which was the problem in the first place and its coming out the overflow hole. I drain a bit, all seems good.

Park in garage one day I hear boiling coming from overflow tank? Strange but nothing leaking. Drive again next day, boiling again now a little less. Drive again boiling goes away, no loss of coolant. A month later boiling loud, coolant sprays out of tank overflow all over the place, big mess. I check no leaks, no nothing, I park car on slope in other direction making radiator highest point, I burp the system multiple times. All seems good, coolant cycling, fan turns on and off, etc. All seems fine. Come home one day and I notice faint boiling sound, but nowhere near what it ever was before. I let it go. Noticed it a few more times but always faint no leaking, coolant levels seem fine.

Fast forward to today, driving home and car never warms up, coolant gauge is full cold, digital gauge shows --- , oil temp gauge is full cold. Message shows on dash saying "AC Turning off Engine overheating". I pull over cooling fan is on, radiator is warm but not hot, engine is warm but not hot. Ran heater hot air coming out. Drive home and after 30 minutes of driving I am able to open radiator cap and not burn myself/boil over. Coolant overflow tank is low but not empty, radiator is full, upper radiator hose was soft (both when I pulled over and when I shut off). Oil does not have coolant in it. NO white smoke from exhaust, engine runs perfect no codes. I am able to touch both engine and radiator and not burn my hands.

Anyone have any idea what the hell is going on? I mean with coolant loss like that I'm thinking headgasket but it wasn't that much gone, and as I said no white smoke at all. No smell of coolant burning anywhere. Also something had to be cooling the motor, it is not even hot or overheating. Is there some sort of giant air bubble trapped in there? Did the water I mix in with the coolant boil off somehow leaving only the coolant (yes I realize thats ridiculous)?

I'm at a loss.....

[frankwjr]

This freakin sucks man...I'm wondering 2 things..first is the coolant pump working but on second thought when the spring broke and they replaced the head, is it possible something in the cylinder was cracked...small at first but now gettin bigger..

compression test all cylinders and check the spark plug tips...hope some others chime in...good luck!

[Redbeard 11]

sounds like thermostat going bad. failing to open at times and failing to close at other times.

[Rogue Leader]

Id think it could be the thermostat except why would i have no temp readings including the oil. I mean theres no way the oil could be that cold.

[Redbeard 11]

and it isn't. i think its a safety measure wired in to indicate immediate attention

[Rogue Leader]

I guess so. I mean theres just no way the oil could be that cold. I just checked it now its clean not milky and it is still warm 2 hours later so it definitely was hot. That said turning the car on the coolant temp sensor still indicates --- and I still get that engine overheating error, the fans are stuck on.

I've ordered a thermostat.

[redcoats1976]

i know that in a pontiac solstice---on the temp guage means thermostat malfunction.since thats the cheapest and easiest thing id try it first.

[Rogue Leader]

So from what I read the oil temp gauge is calculated and not actual temp, which now makes sense since the coolant temp sensor isn't working.

That said it doesn't make sense that the sensor would fail and the thermostat be bad at the same time. I feel like maybe water is not getting to the sensor.

I'm gonna change the thermostat, but I think i'm gonna need to do the water pump too. I think water is just not getting to the sensor. Does anyone know if these water pumps are cheap plastic impeller?

[redcoats1976]

i would do the thermostat and hope it fixes the problem,it worked for my solstice.

[Rogue Leader]

At a minimum the sensor is bad too. If I turn on the car it gives me the same error about overheating and no temp display. Obviously the car is cold at this point.

[Rogue Leader]

So I changed out the water pump, thermostat, and sensor. Start the car up still have the error. Pull the battery cable for a few minutes, start again and everything is perfect. Cycled everything a couple times, everythings working, no more boiling, no leaks. So whatever it was, I fixed it.