Ok friends, I'm very very close to purchasing a local 1979 300SD. No rust, good body. Good interior. All happy and working. Great docs.

Minor details in question:

Cruise control doesn't work... speed decreases when you let go of the switch. If you hold it, speed stays. Easy to find/replace the part?

Tachometer doesn't work... easy find/replace?

Sunroof works, but is quite slow to close. Is that normal?

A few brake hoses that need replacing and driveshaft cover has a small crack. No shaking though.

Rear window doesn't work. Panel was off, so owner was in progress. What's the worst case on a window motor/switch?

Will post pics when I get. :-)))

Look for rust, carefully. They always rust...feel around the floors for soft spots as the undercoating might not be damaged but no metal on the other side. Look around the frame areas, under the back window, rockers, jack points.
Power windows are never a big deal, but the parts are expensive-usually a striped tooth on the lifter (scissor type set up). Check for power first, the switch has to be hooked up in the door.
Cruise almost never works, again parts are expensive. It is a fairly simple system with lots of online diagrams/how to's. Run through all the steps before assuming it is one part, test everything!
Tach again almost never works on these old beasts, not so expensive and very simple just a pick up, amplifier and gage. In my experience used parts from either the cruise control or tach seldom worked, it was a weak spot on these cars so deal with rebuilt or new stuff to save grief.
Sunroof is likely dried up, some lube should help. The cables run all the way into the trunk, you need someone that understands the system before you tackle it, pull the cables, clean, and possible lube not sure what to use do a bit of research. Grease the slides and contact points in the roof where parts move. This can be a big job (a few hours) and def not everyones cup of tea.
Enjoy the car, ours has been in the family since 1986, love it. Things to improve, tires/size the 14" is overwhelmed! Headlights, either euro or conversion small round lights.
Grab any spare parts you can find, they are getting very rare to find.
Consider a manual climate control (European) when the auto dies, it is full of expensive parts.

Sounds like a good find. I have owned a 1980 300SD for 8 years and it has been very enjoyable.
CC may be an easy fix or not. If not, replace the unit with a Rostra electronic or similar. Retain you current CC control switch.
Don't have a sunroof so can't respond on that.
Brake lines are not expensive and straight forward to replace.
Driveshaft cover should not pose a problem. Had mine off once and it's thin steel if I remember correctly.
Watch the HVAC unit under hood. It can fail and leak. I replaced mine with an Unwired unit and never have had anymore problems.

I've put about $2000 into mine just in parts in the last 6 months since buying and my car only had 80K miles on it. I've put about 100 hours of labour into it so far. Don't buy this car unless you like dirt and rust in your eyes and own a lot of tools!

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1987 300E

Did the owner repair things before they broke? Or did he just repair the things that would keep it from being driveable? Was it being driven daily or stored and not used? That's the big question. If it's just somebody who did the bare minimum then I'd avoid it because everything on the car is likely to be worn out and dangerous.

My car was stored for 8 years. But the car was in good condition mechanically and the body and interior are great. But so much stuff needed to be fixed. So much stuff. The little problems are endless.

Oh I guess I'm up to 122 hours of my time into it. I also include the time I have to spend researching things and ordering parts.

Mercedes repairs completed:

72500 miles
Oil & Filter change 15w-40 Rotella
Replaced front right brake caliper 2h
Replaced vacuum shutoff valve at injection pump 2h
Performed brake fluid flush 1h
Replaced left headlight & adjusted headlight aim 2h
Clean and greased sunroof track 1h
Adjusted windshield washer squirters 1h
Greased front seat tracks

74600 miles
Cleaned previous oil pressure gauge leak oil from carpets 2h
Cleaned oil from under dash 1h
Replaced instrument panel lightbulbs
Replaced windshield wipers
Removed excess transmission fluid 1h
Removed brittle/disintegrating horse hair cushioning from rear bench 2h

76200 miles
Replace dash speakers with Alpine SPS460A speakers 2h
Waxed roof (heavy oxidation) 3h
Waxed hood and fenders 3h

76700 miles
Adjusted valve lash 7h
Installed all new air filter housing rubber bolt mounts 2h
Disconnected EGR valve vacuum circuit due to leaky 3/2 vacuum switches 1h
Inspected vacuum control switch for proper vacuum at transmission through throttle range 1h
Installed new valve cover gasket
Inspected timing chain stretch 1h
Install new alternator & power steering belts 1h
Install new main & fuel filters and seals and o-ring 1h
Replaced filter to injection pump hard fuel line 1h
Replaced all glow plugs and reamed carbon from chambers 2h
Cut and installed new fuel injector return lines 1h
Install new shift linkage bushings 2h
Replaced fuel cap
Replaced radiator cap
Replaced oil fill cap seal
Installed new Firestone Winterforce tires
Cleaned all rear light bulb sockets and replaced all bulbs 2h
Inspected and adjusted right rear window. Regulator misaligned. Disable window switch temporarily at door panel. 2h
Replace trim moulding clips right rear door 1h
Replaced 3/2 valve levers 1h
Replaced radiator auxillary fan temp switch 1h

77800 miles Nov 15, 2014
Replaced fuel filler neck grommet. 1h
Replaced foam pad in rear seat. 3h

78500 miles December 18, 2014
Oil and Filter change. Kendal 15w-40 semi synthetic.
Added power steering reservoir cap gasket.
New spare tire well drain grommet. 2h

79000 miles December 21, 2014
Checked rear differential fluid level
New muffler hanger donuts
Installed manual heat control valve
New air filter
New thermostat
Waxed rear quarter and trunk lid
New fuel hose at engine (line to pre-filter to lift pump)
New primer pump
14h

79300 miles December 31, 2014
Oil change 5w-40 Rotella T6 synth.
Transmission oil and filter changed.
Castrol Dexron III ATF used.
Throttle linkages adjusted per MB specification and lubricated.
Fixed slight oil leak at oil pressure gauge.
9h

79500 miles January 13, 2015
New Monark Injector nozzles 4h
Install new gas pedal bushing 1h
Add plastic guard to oil pressure line at firewall opening
Lubricate seat slides & trunk hinges

79800 miles January 30, 2015
Replaced front left brake caliper
Replaced brake pads on both sides
Due to brake fluid leak 5h
Replaced all capacitors in turn signal relay 3h
Replaced lower intake housing seal at turbo.
Sealed valve cover nuts with gasket maker and copper washers. 1h

80,000 miles Feb 9, 2015
Remove steering lock assembly 10h
Remove bad ignition lock cylinder 4h
Install new ignition lock cylinder and old steering lock assembly 10h
Installed new oil pressure gauge line
Lubed steering wheel bearing
Lubed horn slide contacts
Lubed heat control cable
Installed plastic shroud around heat control cable
Glued headlight bezel cracks
2h

81,000 miles February 28, 2015
Replaced ALDA line from intake manifold to switchover valve. 2h
Replaced rubber PCV hoses from air cleaner to valve cover. 1h

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1987 300E

My back window doesn't work because the regulator has a worn guide so the gears slip. Parts can be found on this site. A few hundred for a regulator and a few hundred for a motor, I will probably try to find a used one in a junk yard or somebody who is stripping one for parts.

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1987 300E

Cruise control depends on the set up, do you have the servo unit?

Tach is usually the amp, getting pricey, a member (James dean, I think) has solid state units for sale.

A slow sunroof is indicative of old grease, clean and replace.

By all means, replace any suspect brake lines.

The window may be a number of things, does it get power?

I'm in Hopewell, let me know if I can help.

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83 SD

84 CD

The owner has been driving the car regularly. He's a CTO (seems meticulous) of a large company and has spared very little expense in keeping the car up. He had a new 617 motor from Germany installed in 2003 and replaced the transmission at the same time... have a stack of receipts organized by date that is 3 inches high. The motor/tranny was done by a Mercedes dealer in Dallas and cost $17K. Car has 280K on it and has been driven. Newer paint looks great. Interior has been redone and looks near new. See no rust at all underneath. Lots of details, including original bill of sale and aid kit and tools and manuals, extra parts, panels, visors, etc... He's chosen to invest in this car over many years vs buying a new one, and for some reason is now letting it go with these few issues... that if I had the shop do would all cost about $2K to have the car totally and completely sorted with everything working and tight. (albeit the sunroof slow... that sounds like a real pain to take apart and grease up) Is a gorgeous fully functional 79 SD with a new-ish engine worth $8K? Maybe to the right buyer, and I guess I'm taking the plunge. Am I nuts? I could buy a really nice 300D for 1/2 that, but nowhere near as sweet (I think) as the W116 SD. Maybe I need to get both and have the 300D as the daily driver. My girlfriend is going to kill me.

Ok for that price you could buy a 2006 e320 CDI.
Remember it doesn't matter what repairs were done 10 years ago. He sounds like a fool. Why buy a new motor and trans for 17K when you could just get a used one. What matters is what the car is worth right now. And right now it may only be worth $4000.

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1987 300E

I'd try to haggle on the price but I don't think it sounds unfair. You have a LOT less to worry about with a replaced engine and transmission, especially if they guy takes good care of the car. IF he has complete maintenance records, that's even better. These old cars can get expensive quick but it doesn't sound too bad for you. I would still budget around $2000 for repairs in the first 18 months or so of ownership.

Look at the price evaluations here:
Price Guide Report
Notice this is Hagerty, this is market value and what they would value the car at. This is not your Craigslist value, Craigslist value is always going to be much less than market value but you are not likely going to find a car like this on Craigslist.

That being said, I agree with rob300SD. You can get a nice modern Mercedes diesel or gasser for the same money. They may not have that classic look or be simple to service but they are much much much more modern. Better seats, much better brakes, much better safety, MUCH better climate control, better availability of parts, and 10 years old vs 36 years old. I'm not saying the cost of ownership would be less but it's just a much more modern, comfortable car.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

If I had 8K Id be buying a 2006 4cylinder Honda Accord. Similar sized comfortable car that will have WAY less issues. Also parts way cheaper and easier to repair. Yeah you would need a $500 code reader but that's a small investment. Car would also be cheaper to repair if you do have to take it in for dealer repairs.

I bought my car for $2500 and it only had 80K on it. I bought it because it was a cheap safe car that is relatively easy to maintain. However these cars are not cheap. Parts are twice to 5 times the cost of the price of cheaper cars. Parts are sometimes really hard to find too. If I had more money I would sell it and get a newer car less than 10 years old. Maintaining these older cars is a part time job. I've owned 13 cars over the last 23 years and this mercedes has been the biggest headache I've ever owned. If I was single with no kids I would just sell it and take the bus or cabs to get around. It just sucks up so much of my time!

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1987 300E

Also I would never pay more than the insurance company would pay out if the car gets wrecked. So you might want to talk to your insurance company to see what they value the car at.

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1987 300E

How much soul do Japanese cars have?

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83 SD

84 CD

None, but it depends on how much money and time one has to waste. If you don't mind spending 5 to 10 hours a week hunched over your engine by all means the Mercedes is great! It's a nice driving car and people really like it wherever I go.

I also don't like inhaling diesel fumes. I've had the injectors rebuilt which reduced the particulate by a boat load, but I still don't like breathing all the toxic exhaust smoke all the time. Diesel exhaust produced by today's diesel fuel and supplements is full of nanoparticles and nobody even knows what the health implications of those are. I don't plan to keep my car any longer than I have to. I really hate having my 3 year old breathing in these fumes as well. It's a tradeoff, I could have bought an old late 90's Honda Civic or something, but those cars are death traps.

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1987 300E

It seems for 8grand the car should be completely sorted with only regular maintance left to do. In my quest for a wagon I've seen pricing all over the place and based on your description I'd put it at about 6500. I agree with robsd you could get a lot of nice cars for this kind of money but I don't think that's what your after. I gotta disagree about 5-10 hours a week working on it and inhaling diesel. I've done a bit in the past but usually have an indie do the jobs too big for me or when I don't have time. I've never felt like the smell of diesel smell has been a problem. I've been drivng my 79 300sd for 8 years as a daily driver all over Los Angeles and have never missed a more modern car. In fact my experience with this car is what made me confident about getting a 300td as a daily driver. I also like driving classic cars (79 is my newest in 23years) and 22-28mpg is probably as good as it gets for a 30+ year old car.