Boiling coolant - Help me before I push this thing off of a cliff

I'm not sure if you find your answer yet, But its a blown head gasket!!
I had the same issue when I bought mine. I took it to the dealer and they kept saying it was some part of the ac that needed cleaning and I told them I thought it was head gasket. So we made a deal that if they fixed what they thought they thought was the problem and they were wrong I wouldnt have to pay. I ended up with some free service. Once the head gasket was fixed problem solved!!

What was your car doing?
 
It's best to use deionized or distilled water in your coolant system, since the minerals in hard water can cause deposits or promote corrosion. But I personally would not be too worried about flushing it with hose water as long as it's from a good municipal water supply and not well water or something. I would definitely reccomend spending the $0.75/gal or so for distilled water from the grocery store when it comes time to actually fill it up.

/offtopic
 
Just a reminder guys, my temp gauge has never gone beyond the half way point unless the coolant went low from boiling/spilling. That said, I replaced the ruptured coolant hose.
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I cut the little nub that goes to the turbo off to make removal easier.

Anyway, I just test drove it for about 20 minutes with no signs of overheating or boiling of coolant, and I did everything from boosting on the freeway to sitting for up to 5 minutes at stoplights. I got home and popped the hood without shutting it down and the coolant was fine. No evidence of spilling/boiling (like seeing coolant on the splash guard below the radiator) was found. I also checked my oil again and I did not find any evidence of coolant in there either. And once again I checked all around the head with a flashlight and didn't see any leaks, nor did I see any white smoke coming from my tailpipe. I'm cautiously optimistic that my car seems to be fixed, for now. If anything else happens, I will of course report back in. Thanks for your help guys.
 
What was your car doing?

It was bubbling coolant right out of the resevior. No over heating at all. The onlt reason I popped the hood was to show a friend the motor in my new car and I realized there was coolant pooled and splashed around the drivers side of the bay. I cleaned it up thinking it must have been from when they topped it off. Then later I parked the car a heard bubbling looked under the hood to discover the issue.
 
OP, you may have had a pinhole leak in your hose before. This would release the system pressure, which is calibrated to keep the coolant from boiling until a higher temp. The fans are designed to come on in a certain temperature range. Basically, without the pressure, the coolant was boiling at a lower temperature than the ECU expected it to. The engine was not actually running any hotter than usual, hence why the fans weren't kicked on.

A related note: although Mazda would never recommend it, it's generally okay to put a higher-pressure radiator cap on, but NEVER, UNDER ANY CIRCUMSTANCES replace it with a lower-rated one. It will release the pressure at a lower temperature and cause this exact problem.
 
did u get the problem fix ? its definitely the cylinder head gasket i had the same problem for almost two years and i tried everything .thermostat ,two radiators ,bleeding air out of the system nothing worked i even did a compression test and it passed ,then one day i got fed up and took off the cylinder head and changed the gasket and problem solved no more boiling or bubbles ,i have alot of friends with this problem .but most people dont want to think its the gasket because its alot of work to take off and install but this if the problem i just want to share this with everyone because i sent me crazy trying to diagnose the problem ,its a problem with these engines dont let them over heat for long stop the car and call for towing i am now a pro in there protege engines from trying to diagnose the problem and the blown gasket does not even look blown it just gets weak after overheating on engines that are over 3 years old so compression from the pistons leak pass the gasket and into the radiator system causing pressure to build and pass the radiator cap and into the over flow bottle and looks like its boiling .
 
sounds like u got shafted man. if u had a coolant/oil mix then ur headgasket has either gone out or there is a problem with ur turbo and the oil is seeping into ur coolant from there.

how does that happen?

I do have a turbo thats burning oil really bad right now....I was never able to get rid of the oil in the coolant (no coolant in the oil). What I meant by the cap and tstat was that it stopped the boiling coolant and over heating, not the oil in the coolant...I know for sure its not head gasket tho...can oil and coolant actually mix at the turbo?
 
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