Not exactly sure what you are asking. There is a hose that comes from a hot source on block/manifold and goes thru the heater core (radiates heat) and a hose back to water pump. Has nothing to do with interfering with motor/head water flow/cooling. You are not shutting off flow to the motor unless you are doing something really funky. Especially when closed 100%. It does not take very much volume away from cooling system. So, yes, it's safe and done all the time. The original valve shuts off 100% too doesn't it?
You may have been told this before but: ALWAYS say what truck, what year, what motor...........no matter what the question is.
