White "gunk"

I am replacing a manifold system and when I took off the hose going to the water neck I notice a good amount of white junk built up around the inside kind of looked like old lumpy milk stuck to the side of the glass....any ways I have a new radiator to replace the old but what would cause somthing like that????? :shrug: 87 gt
 
Possible excess sealant from the lower row of head bolts that go directly into the water jacket. Each of the lower head bolts is supposed to be coated with a sealant to keep them from seeping coolant past the threads.

The local speed shop in my area (Powered By Ford) said to use teflon pipe dope, which is white.
 
pull the heater hose off your water pump, put a garden hose in the radiator, turn on hose and run engine till you get pure and clear water out of it. only thing is to get out as much water as you can out of the engine, put in pure antifreeze when done, look in your repair manual and find out the water capacity and put exactly half of that in for coolant the rest shoud be water.

also if your new radiator is bigger you need more coolant in it