Originally Posted by Jim7231
This is where I'm going right now. Also, checking lean and vacuum stuff. Then to #1 with hood off trial at highway speed.
I will be surprised if the hood make a difference at highway speed if you are not having issues in the city. A water cooled engine does not rely very much if at all on block surface cooling from ambient air.
I have seen several vehicles that don't have the heater connected and the block plugged that the internal pressure keeps the thermostat from opening.