Having "air pockets" in the coolant system has always been a concern of mine when working on the cooling system. Wonder how Ford "did it" when these vehicles were rolling off the production line?
IDK, but would it have killed Ford to add a bleeder valve to the SOHC cooling system? Almost EVERY time I've had to mess with a SOHC cooling system I've had to fight trapped air. I only recall once where I didn't. My new-to-me 2009 Fusion 3.0L V6 has a bleeder valve right in the middle of one of the rad/heater hoses. Probably cost Ford $.02 per vehicle to add it. I've never had a problem with trapped air on any of my 5.0L's.
There are little tricks you can do to avoid the issue (ie place an aspirin in the t-stat to hold it open, warming the engine up with the truck's nose high and leaving the rad cap off, drill a small hole in the t-stat's plate). It's still a PITA. When I put my ST's engine back together (I will be installing a metal t-stat housing) maybe I'll add a small bleeder plug to the top of the t-stat housing.
It seems to me that Ford (and other manufactures) just loves to do things in such a way as to hasten the demise of your vehicle and to make them nearly impossible for DIY'ers to work on them. Things like...
- No bleeder valves in their cooling systems
- No drain plugs on trans pans (I add them)
- No cooling system block drains
- No dipsticks on their auto transmissions
- So called "life-time" lubricants/fluids
- So called "permanent fuel filters" inside of their fuel tanks (my Fusion)
