I thought I would add one final comment.
I spoke with Dennis O. yesterday, and asked how he'd suggest this thing be plumbed...
Run a line from the T-stat housing to the heater supply (add a manual valve to keep the heat out in the summer), and check under the dash to make sure that the line that is supposed to be going into the heater is attached to the correct port.
Run a second line from the bottom of the overflow tank to the small inlet on the water pump.
No need for a "tee" in this setup.