There are many misconceptions about EGRs blanking plates etc -
#1 - you might think a working EGR valve would be best for your car/ engine, as this was how the car ws designed - WRONG:- even a brand new EGR valve in perfect condition contaminates the inlet (including the manifold, inlet ports etc) with carbon, causes hesitation, flat spots etc - a working EGR valve is BAD NEWS for your engine
#2 even if you clean out your inlet manifold (this requires taking it off and cleaning it with petrol and/or a high powered jetwash) every so often, if you are running an unblanked EGR it will eventually just fill up again - this can "choke" the engine - once you fit your solid plate and clean out your inlet manifold, the innlet manifold will stay clean - so no need to continually clean it out
#3 the whole concept of recirculating exhaust gasses (a waste product) and feeding them back into the inlet is a bad one, diesel engines run best on clean air, and diesel - not exhaust gases - its a bit like a human eating his/her waste - not good
#4 on modern deisels, the EGR valve opens only at part-throttle at lower revs - this is when you get the flat spot (aka hesitation or lag) when the enine ingests burnt exhaust gases instead of air (the burnt exhaust gases reduce or prevent combustion because they do not contain oxegen like air does)
#5 Any emmission control system that reduces MPG (even by a small amount) may have a worse long term effect on the enviroment due to the enviromental impact of having to produce more fuel - a diesel without a DPF or EGR is more efficient, energy and resources do not have to be used to produce the DPF/EGR, + when the DPF/EGR get filled up/ old or faulty, tey can have a worse effect on emmissions than not having one.
#6 - often, these things are political rather than technical, eg eurocrats/ politicians say "look what we are doing to help emmissions/ the enviroment" - even when they don't really work
#7 - when the car/ engine is new, the EGR valve may help emmisions, (but even then has a negative effect on MPG, performance efficiency, and that extra (even small amount of) fuel (multiplied by all the cars fitted with an operational EGR valve) can have a worse impact on the enviroment compared to not having an operational EGR valve - as the car gets older the inlet gets choked up, further reducing MPG, performance and efficiency, and increasing smoke output (or choking up the DPF, if one is fitted) this is even assuming the EGR does not fail, as if it does things can get much worse than that (with a leaky or permenantly stuck open EGR valve the car can produce a smoke screen james bond would be jealous of)
So the long term negative effect of fitting an EGR valve in the 1st place (or running without a blanked/ disabled or deleted valve) may be worse than running with a solid plate(etc), on the envioroment , as well as definately for reliability, elimination of flat spots hesitation and lag and preventing the inlet being contaminated
#8 after a solid plate is fitted there is no problem with moisture/ rust, draining water as the EGR valve is disabled anyway
#9 it is not nessesary to fit the solid blanking plate on the EGR cooler on a mk3 mondeo diesel, it can be fitted next to the EGR valve you can get solid plates that slot in (you don't even need to take the nuts off, just loosten them) - a solid plate is essential, ones with holes defeat the purpose of the plate, the EGR valve must be working properly to fit plates with holes, a solid plate can "fix" a faulty/ leaking EGR valve, by effectively disabling it - 2 solid plates can also be fitted (one next to the EGR valve, another next to the cooler) and the egr pipe removed
#10 the EGR valve has a design fault - it exists!
I am an engineer, I designed/ developed the first EGR delete kit for rear-mounted EGR Mondeos,about 9 years ago then improved the design, this has been copied and made into a commercial product, i have been an advocate for fitting solid plates and have advised and encouraged forum members to fit solid plates, and have helped to promote the resurgence of interest in the subject
I collect information on the subject and listen to feedback from members/ Ford owners that have fitted solid plates, i try to discourage misconseptions/ misinformation about the subject, especially from those that have never fitted a solid plate or understand the princepals etc
I suppose with the 9years of running without an EGR valve (i don't and wouldent have one on my car, i sold mine on ebay years ago!) + designing the delete system + following the subject for years + my technical knowledge = my involvement in advising/ discussing fitting them on the forum must make me an "expert"
I understand others have their opinions - and they are entitled to them, it is a subject i feel strongly about and don't mean to cause offence, of even to discourage members to express their opinions or to debate this, or other topics