hi, i'm new at the club here..
i just replaced radiaror at my mazda 3 2004 2 litre and i wanted to know how to bleed air out of the system. is there any valve to open or other way of bleeding the air out of the system? the heat unit shows also sometimes overheat and the internal heating in cabin is not too hot. pls help..

 

Did you get the mazda bead out properly?

 

I've seen plenty of posts online about bleeding the air out of the mazda 3 coolant system. I live in MN and it is really cold. I tried them with 0 success. Tonight, I installed a short piece of clear plastic hose in-between the heater core hoses to see what was happening. I took a video and I'll try post online later. Essentially I could see clearly all the air in the system...when revving the engine the air is in the coolant and was very visible. When you let the engine get back to idle, the air would pool up at the heater core and stop the flow. The key to bleeding the air is quite simple. 1). I'm assuming your issue is air, not a clogged heater core. 2). keep heat off inside the car 3). let engine warm up....I ran mine at 2500 rpm for 10-15 min until I saw coolant starting to flow into the overflow / shunt tank. There are 2 small hoses going to the top of the shunt tank....the one on the drivers side goes to the radiator...the other one goes to the water outlet valve. It was only when the tstat opened up that I started to get any flow from the water outlet to the shunt tank. Once you see this flow, then run for 5 min at 2500 and the air will come out. I did my car and a friends...and this procedure worked great on both. Again, the key is getting the tstat to open. In MN with the heater on...the tstat would not open, no matter what you did. So keeping the heat off allows the engine to warm up more....causing the tstat to open and the flow to start flowing. Hope this helps.