did a bit of troubleshooting of the brakes today, let me walk you through what I did and my thinking process
since one side (passenger) appears to be fine we have something to compare the bad side (driver) to
so I lifted the front end with the wheels still on off the ground
(secured by jackstands behind the front wheels, not visible in the pics) and:
1. simply spun each wheel by hand to see if one wheel had more drag than the other - not really
2. I did the hands on 9:00 AM and 3:00 PM wiggle the wheel back and forth to see if there's excessive play - not really
3. I did the hands on 12:00 AM and 6:00 PM wiggle the wheel back and forth to see if there's excessive play - not really
with the wheels off
4. I inspected the pads for even wear and how much meat they still had on them, and all four showed equal wear and plenty of meat, look brand new(ish) as they should
5. I tried to spin the rotors by hand and the driver side seems a bit harder to spin, but both sides had some drag that they wouldn't just spin freely
6. with a large flat screw driver I gently pushed the piston back into the caliper on each side and spun the rotors by hand, with the pistons retracted both spun easily the same, no strange noises
7. had the wife start the truck and apply the brakes, I watched the piston emerge ever so slightly but enough to stop the rotors, then I would manually push it back with the screw driver and have her do it again
8. I inspected the rubber hoses
9. we bled the front brakes, 10 pumps and hold it, three times
10. I priced some brand new calipers on AutoZone and NAPA they are cheap $22 bucks a piece
so I will take the truck for a test drive tomorrow and check the external wheel temps again, maybe miraculously the driver side wiggled itself loose, if not it's new caliper and rubber hose time