Cooling System Mechanics and I are Stumped! What is the problem with my 2001 Protege?

Ok, so this is a frustrating problem that my cooling system mechanics and I are trying to figure out. Please read below and see if you can help us out, it would be very appreciated!

So I own a 2001 Mazda Protege and when I drive my vehicle for more than 7 miles the anti freeze starts spewing out of the coolant reservoir. The mechanics checked the whole system doing pressure checks, checking if its a thermostat or head gasket problem, but concluded that everything was running exactly how it should. From extensive tests they were stumped and recommended that I get a new radiator rad cap because it might not be holding the pressure like it should and air might be leaking in. I got a new radiator rad cap and a new hose, it seemed to help a little, but the problem still occurred. Heat blows and a/c blows very well along with the temperature gauge meter right in the middle. Also, in addition, before I brought it to my mechanics I flushed the radiator system and added a head gasket repair mix that the auto store recommended, I let that set in for a day and dry out then reflushed the system again and added new anti freeze.

I don't know if this would help solve anything, but when I bought a new radiator rad cap for my manual Mazda Protege it didn't fit, but the radiator rad cap for the automatic Mazda Protege did. It seemed the radiator system got changed down the line or something?? It's a Canadian car as well.

I feel like I've done everything, what could I be missing?? Any suggestions would be very appreciated.


Mike

Your description sounds like a leaking head gasket. Combustion pressure is a couple orders of magnitude higher than your cooling system pressure test, so no surprise it didn't find anything. You may have only needed a head gasket, but the snake oil you put in the system will leave a coating on everything it touches and may plug up small passages like in the heater core and radiator, so now the entire cooling system is suspect. Find a better mechanic and stop doing stuff to make it worse.

Did they perform a hydrocarbon test? If not, have it done, and by someone else.