put in a new rad and water pump the other day. didnt notice anything out of the ordinary when changing it. prior to changing the car ran 100% fine aside from a small leak id have to top off every now and then

now when i drive the car it pisses water into the overflow tank pretty quickly and overflows. the airs been bled out a good deal-maybe about 20 min. i drove it for a short distance and the temp started to raise a bit so i cut it quickly. reservoir was filled. today me and my buddy flushed the engine from the block drain plug with CLR to clear any blockage in the passages and now temp seems to be steady but overflow tank is still filling quick

so far ive replaced these parts with new mazda units aside from rad:
-thermostat
-rad
-rad cap
-water pump
-rad to overflow tank hose

obviously everybody is quick to jump to the "bad coolant seal" answer but i dont believe that to be the problem. water doesnt smell smokey, car doesnt smoke, no apparent bubbles when doing the geyser test etc and car drove fine up till now. it just seems like theres possibly blockage somewhere forcing the water out into the overflow tank. any ideas or input would be appreciated

car is s5 NA

 

Has the heater core been "open" for any of this flushing and bleeding?

 

yes heater was on full force when i was bleeding

 

i will suggest you do a cooling system pressure test.

 

trying to get my hands on one now. gonna try bleeding it again to see if i can get any more air out in the meantime

 

Consider lifting the front of the car a few feet to ensure bubbles get to the rad.

 

went to try to bleed more air out and there was never ending amount of bubbles coming out. revved it up and geyser 2k15 out of there

coolant seals looking pretty done. gonna borrow my friends pressure tester this weekend for the hell of it but im sure i already know the answer :l

 

That sucks, especially after all the effort you've put into the cooling system, but looking on the bright side: chance to play with porting.

 

CLR in the engines coolant system? Is that a good idea?