This is my first post, but I've already gotten tons out of this great forum by browsing around for a while.

I'm looking for your advice on an '81 300TD turbodiesel wagon I'm thinking of buying. It's a lifelong California car, no rust, never wrecked, no body damage, paint is good, 161k miles. It looks like the owner wants $2,500, but it has a few problems: lumpy idle, is VERY slow off the line, AC doesn't work, two of the windows don't go down, the motor has a slight oil leak, and the trans shifts pretty hard. The owner also said there is a noise in the rear end, but I didn't notice it.

Another concern is that there are no maintenance records. The current owner bought it at auction and has only owned it a short time. It's not advertised for sale, I just noticed it in the neighborhood and asked the guy. He says he will sell because he has too many other projects.

Otherwise, everything is intact and works and the car drives great. The interior needs a cleaning but is in perfect condition except for a wear area on the driver's seat. The self-leveling rear suspension appears to be working.

From my reading, it sounds like several of the problems could be caused by vacuum leaks (windows, idle, poor accelleration). Or could it be something worse? Do you all think the price is fair? Is there anything else I should be looking for?

I've never owned a diesel but have done all my own car repairs for more than 20 years. I am interested in running this car on biodiesel if I get it.

Thx in advance for all your help!

It sounds like you are looking at a pretty good car. A lumpy idle could be dirty injectors or more likely it just feels lumpy because of bad engine mounts. Neither is hard or expensive to fix. The slowness off the line could be a simple clogged air line to the ALDA. If you aren't seeing a lot of smoke or other signs that would suggest a bad turbo or worn engine then that too should be an easy fix. The windows are not vacuum powered so that may be a bit more complicated. The motors are pretty robust but the regulators and fuses do often cause problems. the good news is that parts are pretty available in junk yards so I doubt you have much of an issue there. The hard shifting is also likely a vacuum issue but that's a bit harder to know without some experimentation. If the shifts are solid and there doesn't appear to be any slipping the chances are good the fix will be simple. The AC is a different story. The compressors are prone to failure and a proper repair (one that will last) requires a new compressor, complete flush and new receiver/drier at a minimum. If you want AC it will likely cost you. Now about the price, others here may disagree but I think the price is on the high side. If the AC where properly repaired I might look at it differently but cars with needs are seldom an easy sale except to people like us who know the cars and can do the work themselves. That said, a 123 wagon with no rust and relatively low miles is a car you could use and enjoy for another ten years. You need to decide how much that $2,500 is worth to you. At a fair price and with a through look over, my sense is that this car may be worth taking a chance on

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Sounds like a pretty good deal to me.

The others covered the lump idle quite well, as for the other things....

Are the two windows opposing corners? If so it may just be a bad connection at the fuse, common problem, $10 solution of getting all new fuses. The windows have nothing to do with vacuum.

I guess "poor" acceleration has to be redefined for a car which weighs 3400lbs and gets 83rwhp on a good day. If it is all around pretty slow then it is probably just a fitting/line clogged up, just clean it out and it should make a world of difference. (alda line)

I didn't think the MB-tex (not leather, but nearly indestructible vinyl) would have wear spots.

Tranny shifting hard is a vacuum leak or possibly a bad vacuum valve. Odds are the noise he is talking about is going into and out of first, this happens when not enough vacuum is being sent to the tranny during those shifts.

Where is the oil leak? As long as it isn't the main seals or head then it isn't a very big deal.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Wow, thanks for all the great responses!

I misspoke when I said the windows could be vacuum related. I meant the central door locks, which also don't work.

BoostnBenz: As a matter of fact, the "dead" windows ARE on opposing corners (RF and LR), so that's promising. But I can hear gears grinding inside the RF door, so it may be worse than a fuse. Owner tells me the oil leak is in the fuel distribution unit on the driver's side of the motor. I'm not sure if that's true or even possible, but that's what he said.

dieseldiehard: I definitely want/need cold AC, so I'll try to use R12 if possible. I know a good local AC shop that, as of last year anyway, could still get R12. ($225 for a new compressor actually isn't too bad.) I'll definitely check those engine shocks, too!

LRG: There was no slipping at all in the tranny, it just really slammed hard on the shifts. I like a hard shift, but this was actually a bit uncomfortable. Anyway, it's good to know it may be only vacuum related. Also, there was no hint of lash or crash in the driveline, even with such hard shifts, so that's a good thing, too.

Another thing I noticed on the car is that the fuel in the little clear filter under the hood looked black to me, and I've read that's a sign of algae, which could explain some of the weak accel. problems, right? I'll have to look again to be sure, but since the car may have sat for a long time awaiting auction, this could be the case, no?

Vacuum problems are quite common on these vehicles, the good news is if you fix one problem it may fix a couple other ones at the same time.

That does sound promising. Are you certain it is a front window grinding? I've never heard of those failing, but the rears are quite common to fail. The unit warps a little over the years, next thing you know the gears aren't meshing right.... It must be leaking where the IP (injection pump) meets the block. That gasket is quite a pain to replace but as long as the leak isn't that bad I wouldn't worry about it.

Yes a black pre-filter implies there is or at least was an algae problem. Unless it is starving the IP of fuel it shouldn't do that much with the acceleration. Sure after it is cleaned out and the injectors are running cleaner it'll help a little but don't expect a big improvement there.

__________________
Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Buy it.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Greetings all. I'm back with an update.

Had the car checked out by an indy Mercedes shop and all looks good. Needs injector return lines, glow plugs and rear brake pads, and a few other minor things. Again this is a '81 300TD with 161k miles.

They did a compression check and found the following:

1. 360
2. 330
3. 380
4. 340
5. 330

How do these numbers look to all you gurus? The shop said this is "within spec" as far as the variance, but I forgot to ask what the normal max compression is, so I don't know what sort of wear these numbers indicate.

Also, he said the oil was overfilled by a quart, but said this would not be harmful for a short period. Your thoughts?

There were no major problems found on the car. Trans and rear end are good. Self-leveling works. AC seems intermittent, so I'll want to get that looked at for sure.

Thanks again!

Just wanted to let y'all know that it looks like I have reached a deal to buy this wagon!

I told the seller I couldn't get him the money for a week or so, he said "fine" and handed me the keys, said I could use it anyway until then. "Consider it yours," he said. "Take it." So I drove it to work this morning and the car just drives like a dream! Really amazing for a 23-year-old car. And it turns out the AC works after all! It's just the center vents that don't open. Even the cruise control works perfectly! Listening to "Car Talk" on the radio in cool comfort with the cruise control pulling me down the freeway was pure bliss!

There are still a few things to fix on the car, of course, but nothing I can't handle myself. Now I just gotta come up with the money! :p

Many thanks for your help. This forum rocks!

I will be keeping the WannaWagon name. Finding this car became a kind of quest. We've been looking for the right wagon for nearly a year, and we test-drove everything new that's available. There was suprisingly little to choose from, and it was all either too expensive, or too cheap, if you know what I mean. This 23-year-old Benz is in better condition than some of the new cars we drove. I kid you not. And the more I learned about biodiesel, the more that became the clear path. So the name still fits, as far as I'm concerned!

TD = to die (for). IMHO, they're the last best car; congratz!

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Never a dull moment at Berry Hill Farm.