Hey guys I just recently rebuilt my polaris scrambler 400 and now Im having an overheating issue. It blows the coolant out the overflow and actually blew the overflow hose off.

I have read about a bleeder valve on top of the engine (did not know about this or how to do it)

Recently replace water pump and everything so I knows it’s not that. This bleeder valve I thought the radiator would bleed the cooling system as normal cars etc.. Am I wrong on this?

Any help would be greatly greatly appreciative. This rebuild has been a process and this just kind of dampened my day when I went to rid it and it started to have this issue.