YAY I fixed my problem. I have been through 2 thermostats, an autozone and GM one, and 2 radiator caps, again an autozone and GM one. It turns out that when I put my new radiator in, I switched the 2 hoses under the cap, so the reservoir hose was not hooked up to thr right spot and it was not building pressure. Where does the other hose go to?

 

you were draining the radiator and the WP... there was a huge pocket of air left in the radiator and the WP housing. Mainly due to it spewing out the cap.

I did the same foul up like 2 weeks ago... honestly search my post.

The resivour connects to the top outlet...and the wp hose goes in hte outlet underneath of it. There's 2 outlest on the radiator under the cap. Thier right on top of eachother.

 

You would think that GM would make the hoses a slightly different internal size so this goof up can't happen, but oh well. Atleast it's fixed.