The flow control valve began leakin' on the heater inlet hose & broke when I was removing the hose from the water pump. The nipple on the heater side broke off the body of the valve, & that's when I noticed the guts of it restrict coolant flow. What is the logic of this? I feel certain someone has probly removed it on their car. Can it be removed without damaging the guts of the heater core due to increased coolant flow? It has no obvious moving parts.

 

It has been discussed before. Some people have removed it, seemingly without consequence. Not sure if it is to reduce pressure to suppress noise from rushing coolant or just for pressure purposes.

 

I looked at the valve more closely today and the nipple that came off is on the water pump side. It didn't break, per say, it snapped off at the flange and can be snapped back on. The internals do have a spring and it seems the higher the RPM the more pressure going into the valve and opening it up. I believe I'm gonna snap the pieces back together and apply some sort of plastic adhesive, reinstall it using worm clamps, and see how it goes. I agree with ya Shoebox, that it is for pressure regulation for whatever reason.