Is there any way Bar's leak copper sealant for radiators would clog up a sensor ?
It has been known to cause problems with ECT sensors and coolant level sensors, even seen it foul up a few thermostats, heater cores and radiators if too much was added, but only those two sensors.
Would it keep the truck from starting ?
Not usually, it could cause it to run rich, if you suspect that is the case just hold the throttle pedal all the way down and crank it over, this position during the crank mode turns off the fuel injectors and allows the engine to clear itself, but once the engine fires release the throttle so the engine won't over rev and destroy itself, and then let it idle for a few minutes to allow it to warm up some and clear out the catalysts and O2 sensors from excess fuel. But like I stated this is rare that it happens, you most likely have some other problem than just a bad ECT sensor. You might want to rent a scan tool and see what the system has for codes before you just start replacing parts.
Sounds like a plan. Seemed like too much of a coincidence that it quit running about 5 min. after I put it in, but the two might be unrelated events. It turns over smooth enough but does not hit. I can hear the fuel pump hum when I turn the key,too.
Update : Hooked up analyzer to it, and got zero codes. Not sure where to start looking again now.
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