Cooling problem help..

[mgnfcnt978]

This weekend I have changed the water pump, thermo, and the rad on my KA. Its a regualr oem replacement plastic top rad for at/mt cars. While changing everything figured my car ran no thermo from previous owner. After putting everything together and bleeding the system with the front jacked up and rad cap opened, took it for a ride the temp spikes up after a like a minute of driving. Checked everything again took the thermo out checked it it openes fine, flushed the system again-car still does the same thing.So i checked both top and bottom hoses. The top one is hot like it usually is, bottom one is cold and the bottom of the rad is cold.

What can it be? Just a shitty china rad that does not let the collant flow, or somehting else? Water pump does not leak and thermo openes fine. I searched through forums but did not find a definite asnwer.