About a month ago I cracked the original radiator in my car autocrossing. I ordered a Mizu radiator from weaksauce as a replacement. I had never heard of Mizu but I thought if weaksauce carried it then i was good. After driving around town with it for about a week I decided to pop the hood and make sure everything was ship shape. The upper radiator hose had swollen to 3x its normal size with air. Our first guess is that the radiator cap that came with the radiator isnt letting any pressure out of the system. But where is the pressure coming from if thats the case? I was told it could be a blown head gasket. I'm going to do a compression test today after work to check for that. If thats the case then I'm going to scrap the motor (mini-me b7/z6) and just do an ls or b20 swap. Is it possible that the culprit is solely the radiator cap? Its rated for 1.1 bar like stock but I can't be sure if thats accurate or not. The spring at least feels the same as the stock one. It does seem hard to get off, like I have to push it down harder than normal to get it to pop off. Maybe the neck on the radiator isnt long enough and the spring is all the way compressed all the time? This is my only car and I need it back on the road asap, any help is greatly appreciated.

 

The compression across all cylinders was 205-210 psi. A blown headgasket isn't likely. I will pick up a new cap and upper radiator hose tomorrow and see how everything goes

 

Update?