Also check the obvious- your fan / fan clutch is working. I would check the lower hose on the radiator while it's running to see if you have adequate pressure coming out.

There should be a considerable difference in temp between the upper and lower hose. If the lower house is still hot, or has low pressure could be a clogged radiator or simply no airflow thanks to a dead fan.

Temp gauge should read accordingly high as well. However if its puking into the tank it's boiling over and it should be in the "red" zone if that happens.

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03 540I (GAK!!)
81 280E (W123)
70 LeMans Sport with pissed off Poncho 462"
1989 Silverado Step Side (under the knife- complete restomod)