What do you mean by "taking the heater out of the cooling system"? Are you bypassing the heater core?
What I suspect is your problem is air in your system. If the mechanics didn't bleed your system of air when they installed your new engine, then air will be trapped in your heater core and prevent the coolant from circulating correctly.
The reason the air is in there is because you have a reverse flow cooling system and the heater core is at a hight point in the vehicle than the top radiator hose.
So when you fill it with fluid, all of the air gets trapped in the heater core. The proper bleeding procedure is as follows:
Jack the front of the car up at least three feet. Then open the surge tank cap and start your engine. Place your heater controls on "High" at max temp, then rev your engine to at least 1,500 r.P.M.S until the engine reaches operating temp and the thermostat opens. (The fans come on) Then squeeze the upper radiator hose several times and watch the coolant inside the surge tank until no more bubbles come out. Finally, fill the system to the proper level.
If I've helped you, please vote for me, as I depend on this to pay my bills. Thanx, Ernest.
Sunday, January 24th, 2010 AT 8:57 AM