My 96 68k Z28 will peg the gauge at 260, scanner shows similar temps. Fan 1 relay per scanner doesnt kick on until 230ish then 2nd fan -both on high- at around 235 but temp still rises. I replaced water pump temp sensor, no change, replaced thermostat, no change. My only other thought is low speed fan 1 is weak, Gonna replace fan 1 motor tomorrow. Car runs fine otherwise. Any thoughts?

Has the fan wiring been tampered with at all? If miswired, they will run backwards..just tossing it out there. I scored an 84 Trans Am years ago for practically nothing because the previous owner couldn't figure out why the car would always overheat, for whatever reason someone cut the wires near the plug....crimped them back in backwards...I know it's a stretch, but would be pretty awesome no?

Is your A/C charged? It sounds like a stupid question, but the ground for the fans is triggered by the low pressure switch of the A/C. Just a thought.