I have a 1985 380SE, used mainly for occasional vacation trips and as a second car around town, April thru Oct only. It has 185,000 miles. I'm a little amused at your statement "after that just kinda let it go until it dies."
I couldn't tell you how many times I've cursed the car when it develops a problem, then I go through the cycle of (1) I need to fix it before I can sell it, (2) Ya know, I kinda enjoy the challenge of doing the fix (usually) and (3) Jeez, it works/looks great now, I can't bring myself to part with it! I add up the hours/days spent working on it, and say it comes to 1/52 weeks a year. Big deal, it's worth more to me as a second car than the measily $$ it will bring at sale, especially in today's market of high gas prices.
OK, that said, I think you should roll up your sleeves and do the following:
- Scrape and grind off the undercoat and rust on the frame area. If it's rusted through (I doubt it is), get a competent welder to patch it (that might be you, of course). Apply a generous coat of flexible seam sealer over the cleaned up/patched area (great as an undercoating, almost the same as MB stuff IMO).
- If you can do the timing chain yourself, it's not a really hard chore. Read up on the procedure here, and in the shop manual...you do have a paper MB manual I trust? They're about the price of an hours labour used on EBay. CD's are much cheaper, but vary greatly in quality.
- Sheepskin covers are a great solution to worn out seats. The padding and springs are easy to refurbish yourself too.
- Any rust that's in there below the window won't be a problem for a daily driver like yours/mine provided there's no leaking into the trunk. Lots of threads on curing water leaks here.
In short, it sounds like you have reached a similar point of ownership as me. The bottom line is: keep it on the road as long as it returns some pleasure to you when you drive it, or at least enough to offset the pains of maintenance.
