To make a long story short, my experience with these cars has been that there are essentially three processes to owning one:
1) Find a car that's cherry to begin with, and keep up on maintenance as it's due. In this day and age, it's very difficult to find a W123 that's cherry, unfortunately.
2) Have a car that's in fair condition and address every issue that there is. In my experience, this is going to cost a
lot of money...as someone once said, "there is nothing more expensive than a cheap Mercedes".
3) Have a car that's in fair condition, keep up on basic preventative maintenance, but don't worry about every last little thing. In my experience, this is the most economical way to run one of these cars...and, if you can live with things like the cruise control, climate control, etc. not working properly or at all, these cars can be very economical...
Going into it a bit further...let me go off your list one by one:
1 new injector - I'm a bit surprised that an injector needed to be replaced. These injectors are much more rebuildable than the Stanadyne injectors on our IDI's, and they don't fail nearly as often. I wonder if a Diesel Purge treatment could have cleaned it up?
A/C complete overhaul- everything replaced! - That must have been hideously expensive!! Unfortunately, the climate control on these cars is finicky and can get quite expensive when parts fail...that's why, when the system fails, so many people just leave it that way. For that reason, IMHO if the climate control is important to you, you're best off trying to find a car that's already had the work done.
all new fuses- it was arcing & blowing fuses daily - That one surprises me a bit, although I have found that ceramic fuses last longer than the plastic fuses that you typically find for these cars at the auto parts stores.
upper control arms - That one doesn't surprise me...the suspensions in these cars was designed more for comfort than for longevity, and in fact I condemned all three of my M-B's on large part due to front suspensions that were in desperate need of rebuilding. More on that below.
door check straps - I'm guessing that these weren't greased regularly. While I would agree that the design leaves much to be desired, I've found that, if you grease them up regularly, they'll last longer...but, most people don't think to look at them.
tie rods - See my comment on the control arms and below.
rebuilt vacuum pump - That one makes sense...
new glow plugs - IMHO that's routine maintenance on any diesel.
Now here's what its needs next:
All new lower suspension - Like I mentioned above, the suspensions on these cars were made for comfort more than longevity, and IMHO is the true Achilles' Heel of these cars. How quickly does the suspension eat front tires? I had a '79 300SD that would eat a brand-new tire in about a thousand miles
IMHO I would look at how quickly the tires get eaten as a gauge of how badly the suspension needs to be re-done...basically, are you willing to throw as many tires at the front as are needed? If the answer is no, then the suspension needs to be redone...and, honestly, that might mean it's time to throw in the towel...although, with all the $$ you've invested in the climate control system, and since you should get a good long time out of the suspension after it's been redone, if you like the car overall, maybe it's worth spending the $$?
new steering gear box - Have you tried tightening up the old box? You'll need to replace the box sooner or later, but you can buy a surprising amount of time by tightening up the box...just keep in mind that the allen-head bolt that tightens up the lash needs to be turned counter-clockwise to tighten the lash.
new oil hoses from oil filter - That one's a fairly common one...my friend who bought my '83 300D from me had towcat's shop do the work last winter, and IIRC spent about $300. Money well-spent IMHO; it's a dirty job involving removing one engine mount...but, again, once it's done, it's done and the replacement hoses should be good for a very long time.
turbo rebuilt - How bad's the turbo? This one really surprises me...OTOH, you mention further down that the timing chain's about due...IMHO both of these are indications that the car's routinely gone way too long between oil changes. With regular oil changes, the timing chain shouldn't be stretching this quickly, and the turbos on these cars generally do well.
trunk seal - Was the car a desert car to begin with? In the Southwest, I wouldn't be surprised by that, but I don't know how long rubber components would typically live in Indiana.
hood release cable and handle - I've seen this on a few other cars...generally, the cable needs grease and/or a gorilla's been pulling too ******* the handle
body work & paint - Paint on '80's cars seems to never last...although, unless you're getting cancer that may affect the structural integrity of the car, IMHO this is more a matter of personal preference than anything else.
driveline flex discs - IMHO take care of both of these ASAP...I've heard some horror stories about flex discs failing and the driveshafts wreaking havoc on the underside of the car
driveline carrier bearing /
fuel cap seal - Should be a simple and cheap fix
side trim molding clips replaced - Again, should be simple/cheap...I think those clips are something like $0.50 each.
timing chain is about due - See my comments about the turbo...timing chains typically don't stretch this badly this quickly unless someone (either you or the previous owner) has been very bad about keeping up on oil changes.
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Given that the car's getting up to 200K miles and sounds like it's been neglected a bit (whether by you or by the previous owner, I can't say), IMHO that list isn't unusually long. I would go so far as to say that, in my opinion, if these issues are addressed and you keep up on routine maintenance going forward, your maintenance list in the future will be much shorter. Keep in mind that, if you use quality parts particularly in the front suspension, you should easily get another 150K to 200K miles out of the components...and, granted I've never owned a Toyota (I don't buy Japanese products when possible), but I don't think that there are very many vehicles on the road that can get 200K+ miles out of front suspension components. One nice thing about M-B's is that, if you use quality replacement parts, you should get as much if not longer life out of the parts than you did from the original parts...so, looking at the climate control as an example; you've already spent a good chunk of change rebuilding it; barring a compressor failure or similar, you should easily get another 150K+ miles out of it.
In the end, it's your call, but I still contend that the W123 chassis is reliable and will last a long time if taken care of properly...I vote for keeping it unless the front suspension's just too thrashed to do anything with.
Just my $.02...
