The Stovebolt Site Forums The Shop Area Engine Shop Heater Core Isolation valves

I was out at the mecum auction in Houston a couple weeks ago, and an old collector was selling about 50 cars out of his collection. I noticed many of the older ones had isolation (ball) valves on the heater hoses both to/from. Sounds like a good idea for autos that mostly sit. How would you drain the core without draining the hole system? Maybe they just close the inlet and outlet valves and unhook the hose on the outlet side and drain into a bucket without draining the whole system. Would that work?

I'll venture a swag. Inorder for the heater core to stay constantly hot, coolant must flow in and out. Which would seem to indicate one feed could be a suction side. Or at least a return to the pump. By shutting off the pressure or "in" side to the core 1st, The suction or "out" feed "may" draw coolant out before its closed.
What they are probably doing is keeping both sides closed keeping the core bone dry and never using the heater.

I dunno, just a swag.

If you stop the flow in either hose it will keep the coolant from circulating but there will still be fluid in the heater core. Stopping it on the pump side might slightly reduce the pressure in the heater but unless you have converted to a pressurized cooling system it shouldn't really matter. I added a simple cable operated valve in my truck so I could regulate the flow from the cab.
http://i99.photobucket.com/albums/l286/Hookalatch/Heater/IMG_1752.jpg

Nice job Chuck.