Hi all, been gone awhile, doing the job hunting thing. Laid off from the semiconductor industry so I've been busy. Anyway, our 66' 289 is running hot now that it's warmed up in Phoenix. Reviewing some past posts, one of the things mentioned was the possiblity of air in the cooling system. I'm wondering if that is why our gauge is reading VERY hot, when the motor seems fine. I can almost hold my hand on the valve cover when the gauge is pegged! I'm wondering if I could have an air pocket in the manifold by the temp sending unit and if this could be causing the high temp reading? The sender is new, not from Ford, it's one of the 5 or 6 dollar units from Mustangs Unlimited. Brand new wiring harness and the gauge seemed to be working ok prior to us draining the coolant a couple times for various services. What is the procedure for purging all of the air out of the system's nooks and crannies? We have tried about everything else ie new hoses with internal springs, new t-stat, radiator like new, new 16 pound cap, 16 inch electric fan with shroud. Any other suggestions? Thanks and sorry about being so long winded!