Re: 6.0 Powerstroke EGR valve after 40k miles
The EGR valve is located directly behind the intake elbow where the tube from the inter-cooler pipes into the intake on top of the engine, a bit in front of the upper fuel filter. It is not visible without removing stuff. It has a plug on top with a number of wires running into it.
To access the EGR valve you need to remove the tube from the inter-cooler to the intake, and the intake elbow itself (4 x 8mm head bolts). Probably the wiring harness needs to be wrestled up out of the way too. I also had the intake air tube/filter housing and turbo outlet hose removed for other work.
The valve is held in with 2 bolts (8mm head), and once these are removed it can be rotated till the mounting tabs are clear and a little leverage with a screw-driver will pop it up and out (for me anyway, if its really caked in you may need something like a gear puller)
To prevent future issues you can unplug the wires to it, which leaves the valve closed and prevents exhaust gas from recirculating into the intake but causes CEL (check-engine-light) in 05+. There are also a lot of after-market plugs and block-off plates that effectively do the same thing but will also cause the CEL and codes. A tuner or computer re-flash would be needed to prevent the codes and CEL on 05+ engines. Any of that is probably not kosher in an emissions-controlled area.
I have no idea what any Ford dealer will say about a coolant filter. I have no faith in any shop's abilities to work on our van anymore, so I just do all the work myself, make the changes I want to, and our warranty is almost expired anyway (much good it did us). I would point out that if you have a coolant-heater installed (like the Hydronic) you could just tap the filter flow off of the lines to it, and not do any further modifications to the factory coolant system, with possible exception of a T to return coolant to the de-gas bottle.