I got around to replacing the valve stem seals, and here's a tip: I ordered the KD tool but my supplier substituted the more-expensive Lisle tool instead. The Lisle is supposedly a better tool because it uses a mechanism that negates having to reset the spring pull stroke for every valve, but I found that its handle kept getting in the way. I'd much rather have used the KD tool with the big knob on top. About $30.
Plus, it was a messier job than I'd thought. The springs are in pockets that are a bit deeper than normal, and every time the spring would pop off the tool, a spray of black oil would arise and cover me and the hood insulation (and anything else withing striking distance). After the second time, I took to draping a rag over the tool and spring to try to contain it as much as possible, and that helped.
I pulled the valve cover again and adjusted the valves after having run the truck a couple of days. You have to have the engine up to operating temp to do this. Spec is .014". I found five valves over .020", two right on, and one at .011". Worth doing. On my non-PS, non-AC, non-EGR SD22, it required a 10mm wrench for the valve cover bolts, a 12mm box end wrench for the valve adjusters, and a GOOD No. 2 flatedge screwdriver for the actual adjustment.
Additional tools that are nice are a remote starter button (for bumping the crank around: be sure to disconnect -- and later reconnect -- the DPC controller at the round harness plug behind the battery), a new valve cover gasket (the Fel-Pro gasket fits nice but does not come with the two round gaskets for the cover bolts, it's about $10), some solvent to clean the inside of the valve cover, some clean-up soap for the engine for when you're done (Simple Green works well, as does the Castrol Purple stuff, which is mostly sodium hydroxide (lye)).
And, of course, a feeler gauge set.
Results? After getting all the glow plugs working, and new valve stem seals, if I let the glow plugs warm ten seconds longer than the dash indicator says, when I crank up cold I get NO (no!) smoke. Wow, I've never owned a smokeless diesel.
This truck doesn't smoke at all on the road. At least, I'm looking right at the tailpipe in the side mirror and I can't see any at all, even rev'd to the governor, even under full load on a hill. Must be something wrong
I am running ASTM D-6751 biodiesel (100%), so that might help.
