A couple for data points on my GMC 228:
With 160* tstat the engine running temperature runs consistently at 160* on the road, prolonged idle to slow driving maybe 170*.
With 180* tstat he engine running temperature runs consistently at 180* on the road, prolonged ill de or slow driving 180*.
On the road the temperature never gets too far off tstat temps. My system is zero pressure system ( stock). The overflow pipe is soldered in the top tank.
If yours is actually running 200-212* first suspects would be the radiator, tstat issue, water pump, water flow blockage, compromised air flow.
Last edited by showkey; 11/03/2019 10:33 PM.
