first off do not do this on the car, take them off and take your time cleaning them without debris falling into your exposed valvetrain


remove air intake
separate breather hoses
separate fuel line on drivers side (have rag ready to soak up fuel)
unbolt coils from valve covers, flip them downward and out of the way
remove vc outer bolts holding vc to head, do not remove access panel bolts yet
remove valve covers from car
wash, we put them in the parts washer overnight and let them soak, will make the job much easier
remove access panel bolts
remove access panels
clean thoroughly without scratching up the sealant areas, I use a plastic trim panel tool so I don't gouge the magnesium with a flat head screwdriver
I run a tap down into the access panel bolt holes to clear out old sealant and chase the threads
are all 4 pieces clean enough to eat off of? if not keep cleaning
lay access panel upside down on bench and apply a 3/16" bead of Mercedes rtv into the channel consistently all the way around
set access panel onto valve cover to seat
access panel bolts are there to hold the panels down while the sealant dries, do not over tighten them or you will pull out the threads in the valve cover and ruin your day
we use new ss bolts as the factory bolts are aluminum and tend to snap easily (so you don't overtighten and rip out lower vc threads)
install new lower vc gaskets
reinstall everything
enjoy


overall the job is a PITA due to all of the cleaning and mess involved, figure 1/2 hour to get them off the car, an easy hour each valve cover cleaning and another 1/2 hour to reinstall onto the car.


years ago when these motors were still new enough I used to do them all the time on exchange, now that the magnesium/aluminum alloy covers are oxidizing and pitting I no longer bother with them, i'm not sorry to not have to do them anymore I promise you. now all the originally installed valve covers are pitted enough that they are not worth coating as the pitting will still show through and look bad.