and I dont think the coolant is moving.

I started the car filled the radiator and then it started overflowing. I would think once the coolant started moving the level would drop and I would need to add more coolant.

what is the best way to make sure the coolant is moving? do I need to let it pressurize before it will start moving? both radiator lines got rock hard so something is not right.

how can i make sure the coolant is moving through the system

 

Did you cut the jiggle valve out of the thermostat and make sure it was facing up. Also you may have a big air bubble. Park the car on a nice incline, or jack stands then start it and let it run with the cap off.

Do you think the pressure in the hoses is water or steam?

 

Circulating liquids are non-compressible and will not lower the reservoir level. Normally a rad doesn't overflow with the cap off until the fluid starts expanding from heat.

You need to burp the system and ensure the thermostat is correctly installed.

 

jack the front of the car up in the air so the top of the rad cap is above any coolant lines and try to get it above the head. Then run the car with the cap off for a few mins. This will get the most of the air out of the system. It will "rise" until caught air bubbles are burped.

 

ok thanks guys, the cars i've owned before had either a bleed screw or a hole in a hose that you pull until it is exposed to the water and all the air gets pushed out and coolant starts to ****. I will jack up on the rad cap side and run it again, I think I got it but I want to make sure, I took half the car so just trying to be careful and make sure everything is right. a nice air bubble can really f- up your day.

 

went out again and no bubbles so I think Im good. had a small leak but got that fixed, a distorted hose clamp was to blame. I think the leak may have been the source of bubbles which is what freaked me out in the first place. thanks for helping a miata noob