I'm new to the forum so forgive me if this has been asked about before. I replaced a leaking radiator and since then the engine only gets to 180 to 185 degrees. Before the radiator I replaced the water pump so that's new and it reached 210 degrees normal operating temp fine after that but only started after replacing the radiator. I've replaced the temp sensor and refilled the coolant using an Airlift vacuum filler. The system held a vacuum just fine but still get gurgling noise from under dash so I suspect there is still air in the system but don't know if that's enough for a 20 plus degree drop in temp.Changed thermostats 3 times now each 187 degree rating. One other thing is rear heat now comes out cold but that shouldn't make the engine run cool I think. Any help would be greatly appreciated. Thanks
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2001 Yukon XL 4X4 5.3 litre engine