I purchaced a mazda 3 2007 aproximantly 5 months ago. About 2 weeks after pulling it off the lot at aprox 59,000 miles the check engine light came on for a few minutes. Didnt think anything of it seeing how it turned off. About 4 months later the heater stopped working for a day, than turned back on. The next day the water temature gage pinned itself all the way up to hot, and the check engine light came on we immediatly pulled over and checked the engine. the coolant was bubbling in the tank but the engine was not hot at all. I drove it back home about 3 miles and it was sputtering and not wanting to go. I checked the coolant tank and the overflow was supeing out coolant. I got it checked into a service station, they said I have an electrical problem. i was dis-satisifed with their service and had it checked somewhere else. They did a block test and said it failed the block test and possibly has either a cracked head or blown head gasket...


It's not showing the symptoms of a blown head gasket or a cracked head, no oil in the coolant, no coolant in the oil and no white smoke coming out of the exhaust. I did not see the block test done with my own eyes, but he said he did it a couple of times and it failed the 4th time.

Im thinking that he's just trying to get me to waste my money so he can "inspect" the head? The car only has 60,000 miles and its only 4 years old, how could head possibly be cracked? It sounds like a coolant censor issue any feedback will be greatly appreicated. It looks like im going to be out of a lot of money on a car thats not even close to be paid off.

 

If it got that hot, the head could be cracked. When was the last time the tstat was changed on that car? By the symptoms (no heater, running hot for a few minutes, then back to normal) it sounds like your thermostat's stuck.

20 bucks and 20 min. Hopefully nothings damaged from the overheating.

 

It didn't actually overheat. When the gauge showed it running all the way hot we took the Infared heat gun on it and it was running at normal opperating tempature.

 

Step one: Bleed your coolant.

You could possibly have air bubbles in your system. Causing overheating issues, sporadic idle (air on IACV), bubbling coolant etc...

Very easy to do! Pop your radiator cap off, turn your heat on HIGH, run vehicle to operating temp, and wait till all air bubbles have surfaced in the system (can take a while)

If problem isn't solved test Temp sensor for continuity.


Hope that helps.