Looking at a '84 300D
 

I've come across an '84 300D with 210k miles. Car is in fair shape, some bubbling on rear above wheels. Some moisture in the car so likely needs window seals. I am going to go look at it more closely in the next few days but I don't really know much about what to look for or if it is even worth it. Car has been sitting for last 6 months but was daily driven before that. I think it will need maintenance that has been deferred ie. filters, fluids etc. Price is $1000.

If at all possible have the car sitting cold when you go to check it out. This will allow you to asses cold start performance. Then take it for a test drive and come back and tell us what you find. Not so well maintained examples present with a variety of issues, many of which are relatively easy fixes, others not so much. These cars are rust prone and you already have some signs. However, for the asking price it's tough to go wrong.

Yeah price is good but still don't want to inherit junk. I know the OM 617 is pretty indestructible but the interior is a bit rough, front seats need to be rebuilt or replaced. I figure if the car is solid I would fix the minor rust and some of the mechanics/cosmetics and have a decent daily driver.

Look over the front upper control arms at ball joint, bushing, and sway bar connection. Rust on the swaybar is a big pain to fix. Pull he dip stick and let the oil drip off. SLOW DRIP is a sign of seriously neglected oil change intervals. If it's below 0C it's very unlikely the car will start without glow plugs.
Look under the car along the entire floor pan for obvious rust signs. Look in the coolant tank for rust and oil signs...

Check under the rear passenger carpet for water/rust.

Don't forget the tank filter
 

3 filters on that car. Tank, small pre filter, and main.

Seats badly worn as far north as Canada is indicative of lots of miles. Sun and heat take far more toll of the interiors in the middle and southern states than up here in Canada.

The seat material is quite durable. There usually will be no cracked drivers bolster on the drivers seat for example at 200k miles.

Odometer accuracy indicated is a problem with these cars. Try to take someone along that has owned 123 diesel Mercedes. This actually may be quite important.

Almost never believe the odometer reading unless positive evidence is there or condition suggests it might be so. Most are still pretty good cars at 210K miles.

You are absolutely right. Definitely will check the odometer. Don't think the trip was showing all zeros which is common when they have failed and stop counting. I've already had my odometer/speedo cluster in my 300CE redone by North Hollywood Speedo.

I've been reading lots of threads and watching some videos on youtube from mercedes source which has been helpful. Going to check the oil condition as well as how it starts and shuts off. Blowby I suppose can be checked with oil cap slightly loose on the cover.

It is a U.S. car so I'm guessing it could have come from a sunbelt state thus the reason for the cracking on the seats.

Besides the chronic natural failure of 123 odometers. These cars come from a period in time when car dealers regularily spun the odometers back to gain resale value. This was epidemic in those days and possibly practiced more on expensive cars. Either way though the practice was all too common.

Looked at the car more closely. Rust on left rear wheel arch seems cosmetic as it is bubbling. Some minor rust by the jack points but it more cosmetic. The rest of the car seems solid. The rockers are solid as is the trunk (removed the spare and it is solid) as are all the floorboards. Battery tray rusted. A little bit of bubbling on left front fender above the lower rubber trim. There is some moisture inside near the sunroof. I suspect the seal is allowing the water to enter but could be the the windshield seals. Hard to say for sure.

The car fired right up but hard to say if it had been run before I got there. Temp gauge was all the way down. No smoke at startup, starts and shuts off very quickly. The oil cap looks like it is not the right one as it is plastic (I thought W123s would have metal oil cap) and the valve cover is covered from the seepage on the cover gasket. Air filter dirty but didn't look oily. Car shifts very firmly, not sure if it needs adjustment or not. There was a bit of a clunk when downshifting. Diff, tranny or flex mounts?

Tachometer doesn't work.. Becker radio there but inoperable. Climate control iffy. Confirmed I could get cabin heat but the auto button wouldn't hold so only high or low fan. Two windows inoperable. Sunroof works.

I figure most of the 30 year old W123s are going to need some repairs and work. I don't mind fixing things as long as it isn't a rust bucket. I would need to get the rust repaired ASAP. What does everyone think? To buy or not to buy?

Well, being in Canada you ought to know more about structural rust issues than we do in the southern states.

Aside from that, I would be most concerned about the engine. If it turns on and shuts down quickly and has good acceleration, those are good signs. You might want to try the oil cap test to see how much blow by there is. You can also examine the air cleaner to see how much oil is in it. Some is normal, but it shouldn't be totally caked in oil.

The transmission is also a consideration. You can check wear by how quickly it goes into drive and reverse and also by putting the car in drive on a slight incline and watching it inch forward by itself. Hard shifting is usually a vacuum problem and most W123s have hard shifting to some extent. You can also check for a burnt smell on the dipstick and the proper fluid level. As long as it isn't making any grinding sounds, there isn't much else to check without pulling things apart.

For a $1000 car, this is about as far as I would take it. You know it isn't going to be perfect, but there really isn't too much budge room on the price. Either you like it and want it or you don't.

Dkr.

It goes into gear fine. As quickly as my 300CE with a fraction of the mileage. Since the rust is non structural I should be okay.

By the way, any way to find out where the car originated from? I ran a VIN check but nothing showed up to indicate its U.S. history. I suppose it could have come to Canada before accurate records for importation were kept. The history that was revealed shows it has been here for at least the 24 years or so. The mileage from smog inspections is consistent for the last 20 plus years so I am fairly confident the mileage is indeed correct.

For the money you probably cannot do better than what you describe in Canada. Although I would want to live in an area parts cars are still available. Or pick and pull yards are present like around Toronto.

This is almost not a case now on the east coast of Canada. Every part will have to be sourced and mailed to me pretty much. Other than the dealer 125 miles away.

This was not a bad situation until mailing rates to Canada went so much higher. . I think these cars, if not exactly collector cars are going to become fairly scare all too soon now.

Maybe it is seasonal but for example ebay listings are way down is a certainty. May just be a seasonal thing or the economy but they are really down for whatever reason.

In the last couple of years I have noticed a decrease in craigslist ads for this vintage of MB diesels in the cold weather around here. A friend postulates that the listings are down as many will not start in cold weather, and you can't sell easily what you can't start. FWIW

Regards,

W.

Reasonable and of course a factor. Still there are very few southern car listings now either in comparison to past years. Any even half reasonable example will still start locally up here in eastern Canada still.

Later half of December and January it makes sense to use a block heater here or the cold engines sound like they are trying to self destruct for a moment or two after starting.

Also with dino oil you can only creep along until it thins out a little but never pull out into traffic with a 240d engine that cold.