When I replaced my water pump, I refilled coolant into the top of the water pump with the t-stat out. The top radiator hose was still disconnected and I filled the radiator through the top hose and then connected the top hose. I added coolant to the reservoir. I started the car and turned the heat on MAX. I let it run a bit and then briefly removed the front-most 14MM plug on the cylinder head to release any air. It's been doin' fine since.

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2012 E350
2006 Callaway SC560