This is a fairly easy service procedure that all Diesel owners should do or have done once a year. Based on the info in your post, you should have no problem with this one.

First, only do this with the engine ice cold. I would not even do it on a hot summer day, as that could throw off the gap. I got in the habit of only doing this procedure in the winter months when ambient temp is below 50 deg-F for consistency. disconnect your vacuum connector, then the valve cover comes off easily by removing the four retaining nuts. I always use the dual feeler gauge method (ie. select a gauge slightly larger and smaller than the spec. After adjustment, the larger one should not fit and the smaller one should fit easily). Be sure you know if you are adjusting an intake or an exhause valve, as they have different specs. starting from the front of the engine the sequence is E-I-I-E-E-I-I-E (E for Exhaust, I for Intake). Measure all the gaps before starting any adjustments, then only adjust those that were out of spec (if it aint broke.......). I made my own wrench set, and that worked well. The large one is for holding the spring in place and keep the valve from turning, while the two smaller ones are for loosening the retaining nut, and adjusting the valve clearance. A remote starter really helps in rotating the engine, but a manual socket will work as well.

Lastly, you may not need to replace the valve cover gasket, I found that unless it is cracked or damaged these can be reused a couple of times. All it does is keep oil from leaking out from around the valve cover, and that is not under any significant pressure.

Good luck.

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KCScout
98 S420 My Wife's Baby
97 S320 My road car
83 300D My old road car (love that diesel)
81 300SD Wife's former Baby
81 240D A fun stick shifter
71 220D My first one