Overheating issue
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Overheating issue
Hey guys, so I have a 2010 Mazda 3 2.0 that started overheating a few months ago so I parked it, well I started it yesterday and the thermostat never opened so I put a thermostat in it and topped it off with coolant (barely level with the max line) and expanded until it bubbled over a little and got up to 220f and finally opened up and ran fine and stayed cool so I drove it to work this morning with my scanner hooked up so I could get watch the temp and it never went above 203f. Well today on break I started it and watched the scanner and it got up to 237f, I turned the heat on and revved the motor a little bit and it went back down to 200f and stayed there but the coolant is still expanding in the reservoir (I bled the heater core when I did the thermostat) the thermostat is definitely opening because all of the hoses were cool when I started it and warm when I shut it off. What’s the issue here? Any ideas?
Senior Member
Joined: Oct 2018
Posts: 10,665
Likes: 233
From: Northern California
Welcome to the forum
You are all over the place with your information????
lets start with basic information the is missing:
From a professional service shop or dealer miles last service done month and miles and what exactly was it. Not DIY!
Now DIY what and when was the last service done before this heating concern.
Why no scanned information from the ECU ? Have you even scanned for DTC?
You cannot go by onboard temperature gauges nor really directly connected to the ECU. You at least need to confirm temperatures with a handheld Digital temperature gun.
Have to check the fan(s). Did you turn on the AC to max and see if the fans activate?
Did you turn on the heater to the highest temperature and see if the air blow at least hot air. The Temperature tool mentioned earlier is helpful to determine if the temperature is at or close to the hottest hose in the engine compartment.
Did you check for oil in the coolant and water in the engine via under the oil cap?
Explain how you bleed a heater core. Your cooling system does not have a head issue in its casting and also the cooling system is self-bleeding. In other words, on level ground if you drained and fill the cooling system it would self-bleed. At any rate the thermostat you installed may have even had a jiggle vale that would have also aided in bleeding the cooling system.
When you removed the thermoset did you test it to make sure it was the issue? generic test easily done by and DIY in a kitchen with a pot of water on the stove.
You are all over the place with your information????
lets start with basic information the is missing:
From a professional service shop or dealer miles last service done month and miles and what exactly was it. Not DIY!
Now DIY what and when was the last service done before this heating concern.
Why no scanned information from the ECU ? Have you even scanned for DTC?
You cannot go by onboard temperature gauges nor really directly connected to the ECU. You at least need to confirm temperatures with a handheld Digital temperature gun.
Have to check the fan(s). Did you turn on the AC to max and see if the fans activate?
Did you turn on the heater to the highest temperature and see if the air blow at least hot air. The Temperature tool mentioned earlier is helpful to determine if the temperature is at or close to the hottest hose in the engine compartment.
Did you check for oil in the coolant and water in the engine via under the oil cap?
Explain how you bleed a heater core. Your cooling system does not have a head issue in its casting and also the cooling system is self-bleeding. In other words, on level ground if you drained and fill the cooling system it would self-bleed. At any rate the thermostat you installed may have even had a jiggle vale that would have also aided in bleeding the cooling system.
When you removed the thermoset did you test it to make sure it was the issue? generic test easily done by and DIY in a kitchen with a pot of water on the stove.
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