Does anyone have any experience with the speedometer running too fast when cold? It works normally when the truck/ambient temps warm up a bit. It is mechanical in my '91 F250 4X4.
First of all confirm if the speedometer gearing is correct by checking the odometer reading. Gearing is incorrect if reading are out by few percent. IF not then the problem is with the magnetic portion of the speedometer and will have to send it off for a rebuild. Sometime tire size does affect the speedometer speed and if you have abnormally small ones that could be the problem..
