Well, it had to happen... I finally broke down and sold a couple other cars to make room for my 1970 280SEL. It was DOA when I picked it up, so I had it trailered home. I was VERY concerned when it wouldn't start with a new battery (but would fire up instantly with some starting fluid). Turned on the key, crawled under the back end and gave the hideously-expensive-to-replace fuel pump a light tap with a hammer and heard the joyous sounds of the pump coming back to life. The old girl fired up immediately on the next attempt. Oh, and in case you were wondering, I DID put fuel stabilizer in it before storage... guess it still gummed up the pump at least a little.

Anyway, when it DID fire up, I got an unhealthy amount of smoke out of the exhaust, and it smelled like it might be running rich. I let it run for 15 minutes or so (happily, the temperature settled into normal and stuck there), and slowly the smoke subsided. I checked and there's still a good bit of pressure coming from the valve cover hose to the throttle body, putting a visible amount of smoke into the intake (though now it's not really noticeable coming out the tailpipe). There's certainly some positive pressure inside the valve cover, but it doesn't seem worse than a lot of other period cars I've owned and worked on. As I recall, the car acted this way when I bought it, though I have no idea how long it had been sitting at that point.

What are your collective opinions on what I should do at this point?
1) Drive it and hope it gets better (i.e. "that could be normal").
2) Put some MMO in it or perhaps some other additive to increase the viscosity of the oil (not necessarily a bad thing in Arizona in late summer)
3) Pull the valve cover and replace the valve seals (and check the condition of the guides)
4) Run a compression test to check for sticky rings
5) Sell it and run ;-)

FWIW, the car is in pretty good shape - it's a lifetime California car, and there is really no rust anywhere. The interior is freshly redone in leather, and the paint is fresh too (not a show quality job, but it's a good 3-4 footer). "All" I have to do is reinstall the A/C compressor and resurrect the A/C system (not an option in AZ!), replace a bunch of wooden window trim, tear the dash out and refinsh the wood (and install a Wunderbar radio I bought for it), and replace the windshield. Plus the 1,000 or so little details that any car that age really needs. Can't wait to get started, but wanted to tap into the collective wisdom of the W108 universe to see what I should do first.

Start it and drive it around a bit. I'd avoid highway speeds for the first week or so. Let everything loosen up before you start replacing stuff. Give the rings a chance to free up, the seals to swell and the valve guides to re-seat themselves. Run a tank of fresh fuel through it to clear up the injectors, pump, etc.

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
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