"New" '81 300SD

[cbeaner007]

Hi Guys,
I just picked up a 1981 300SD with only 75,782 documented miles. I have full maintenance records since new and it really is a one owner car. It belonged to an elderly lady whose husband used to drive it, but after his death in 1989, she bareley drove it. Carfax was completely clean and literally everything on the car is original to include the Becker Europa Cassette stereo. Even the cruise control works. I ended up paying $9500.00 for the car...did I do OK?

I have only owned 1990's E type diesels in the past so I was wondering what the general forum opinion on this particular model might be. Also are there any particular items I should have checked or watch out for with this car.

The only defects I can find so far are as follows:
1) Tachometer not working-where is the tach sender on this car?
2) There is some growling when backing up slowly, maybe a drive shaft carrier bearing. Doesn't sound like a wheel bearing. Might be a CV joint...any other ideas. Transmission shifts well, doesn't seem to be trans at all. It does have a "clicking" component to it.
3) Instrument panel lamps not working. It's not fuse related. I haven't pulled the instrument cluster to look for loose connections, etc.
4) AC not working. Previous owner told me the climate control module needed to be replaced. Freon was recharged in May and it was working at that time. Is is common to need to replace this?

As always, thanks for any and all help!

CW

[ajohnson1]

Same color as my '82 300SD. Price seems a little high, but not sure what they go for there. I paid $3100 for mine with 147K on the clock, needed A/C compressor adn recharge and nothing else.

[vwbuge]

That price seems a bit much. Nice car though.

[JimmyL]

You paid just about as much as is possible for that car, but documented low mileage can be your justifier. For that price that AC ought to be working!
You have a very nice and clean car. Some cars can never look like that anymore no matter the price, so from that standpoint you get real value.
I'll let others chime in on the tach. I'm a W123 guy, so I'm not sure of the similarities or differences.
Enjoy it!

[Jim B.]

You did very well. Low mileage sells, and peole would pay more than that for one on ebay.

That is the most bulletproff of ANY W126 in my opinion. For a diesel it really IS like new., though you may have to catch up with age related things, such as perished rubber and so on.

[lonewolftek]

Ahh, nice one, looks to be the same color as my '83 SD.

Price is a bit high - but if it is really well documented, and you are the second owner, it's worth it. Garage it, drive it on Sundays, and keep up the documented maintenance!


Tach sender is on the driver's inner fender, behind the glow plug relay module. Unscrew it, pull out the module from the can, and put a cigarette butt in there, pressing against the top. That fixed mine!

If you can get at least the rear wheels off the ground you can disconnect the flex discs (and check them!) and isolate the noise to either the driveshaft or diff/CV joints.

I have to tap the top of the cluster to get my instrument panel lights on - REPLACE the fuses, don't just visually check them. Fuses that 'look' good and even have continuity can fail to pass enough current. If that doesn't solve it, there's a guide somewhere here on opening up the cluster and repairing a few solder connections. Be glad you have an SD - no oil pressure or speedo cables to worry about, it's all electric!

AC problem might be as simple as replacing/fixing the CCU - once again, solder connections can break down after 20+ years of vibration, humidity, temperature cycles, etc. Could be a number of other things though - does the compressor come on (ie, clutch engages)?

Is your AC still full of R12? Both of mine are


When you get to 100,000 miles, take it to the dealer for service, and take pictures of the look on their faces!

[lonewolftek]

Oh, one thing to watch out for - on both my SDs, the rear window regulators are shot. There's no limit switch on the motor, so it's possible to bend the arms by pressing the button when the window is already fully up/down. That combined with the brittle plastic slider (and if the grease is original, it's not lubricating well), will break the slider out of the track.

The slider is a ~$4 part. The whole regulator is $150+.

I have no idea if this is typical of other SDs, just my own experience.

[hangit]

Looks great and not to make you feel bad, but is 3 times what I just paid for my 83 300SD one owner with 146K miles and working A/C. So far mine is a smooth ride.

John

[toomany MBZ]

I won't comment on the price, as I paid $10,000 for my CD with 83k on it, over three years ago. The CCU's are common failures, does your fan run at different speeds in any of the other settings? Engague th EC button and adjust the temp wheel, give it some time. Iis it just the A/C not working?

The tach has been covered, that fix was temporary on one of mine. the price of a new amp has gone up considerably in the past year. That should be working for the price.

JimmyL, most of the underhood is the same as a 123. I'll agree with A/C should be working too.

The clicking sound sounds like a CV joint, while you have the rear end up, floor jack under diff, jack stands under jack points, rotate wheels, listen.

Agree with lone... replace all fuses with the copper ones. However, the non lighting dash may be dimmer switch related, play with that a bit. Those dimmers are a weak point, if you have to pull the cluster, solder the leads together, you won't have any dimming adjustment, but the light will work.

Having said that, I very much enjoy my SD, I drive it during the work week. Best riding car I've driven. Keep the area between the firewalls clear of leaves etc.

Happy motoring.

[Austin85]

You should be able to replace the ACC unit for 150. I believe.

I have an 81 SD in nice shape with everything working and the ride in these SDs has been described like

" Dancing with a fat lady , who really knows how to dance..."

So you should enjot this Highway Machine for a long time to come. Price on an older MB is always relative.........It is a collector car so it is worth what someone else pays.

Someone gets lucky for 3,500 and someone else is fine paying 10,000.

Fix the minor issues, put in a new CD player & 4 new Infinities or MB Quarts and Enjoy !!!


AA

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[123Guy]

Nice car, you will come to love it. My wife has been driving her 300SD for the past 25 years and she wouldn't part with it - people come up to here all the time and tell her if she ever wants to sell it call them.