Hey guys, I'm new. I've been lurking for a bit and this seems like a great community.

I want to start homebrewing biodiesel very soon. My commute to work is long and I do a lot of interstate trips over 300 miles, and I'm a student with little money, so the cost benefit for me is a big incentive. I'm also a hobbyist by nature and love tinkering with all sorts of stuff, so I want to get into working on diesel engines.

The W123's seem like a no-brainer for someone in my situation. Everything I've heard says that they are indestructable, safe, and a joy to own and drive. The IDI 616s and 617s are ideal for my purposes as they are flexible with fuel, and I gather that they are fairly simple to work on. Awesome.

My question for you folks reguards private party pricing on these cars. I live in Portland, OR and the BioDiesel and SVO craze has hit here in force. When I look on craigslist at the cars available in my area, they are both numerous and very expensive for theor mileage and condition. A good condition 240d with less than 200k miles is going for around $2000-$2500 (which doesn't seem too outrageous) but folks selling 300ds and 300d turbos are asking anywhere from $5000 to $8000.

I would really like the turbo and the higher gearing (I do a lot of freeway driving), but I don't think that $5000 is a reasonable price to pay for a car that 25+ years old and has over 150k miles on it. Am I wrong?

KBB has no info on cars this age, but the oldest 300d they have info on is priced at around $3500. NADA puts them at around $5k, and edmunds at like $2k. I don't really know what a good price for one of these cars is.

Could you folks shed some light on this?

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-1991 Ford Ranger: multicolored and the clutch is gonna die.
-WTB w123
-Aspiring Biodiesel homebrewer

Welcome to the community! Let me clue you in on something real quick. If you're a college student with no money, an old W123 will get you around fine, until it starts to break down. Yes, they're fine cars, but they are old, and they do age. Unless you have the time and expertise to fix every little thing yourself, you're going to need some $$$. There's also the cost of proper parts. You can cheap out on parts if you want, but some of us have learned the hard way that the more expensive, OEM way may cost less in the long run.

AND, they're not quite THAT flexible on fuel. Feeding it the wrong fuel will damage the IP in quick order.

You can't go strictly by miles. Past maintainence also plays a big part in whether the car is good or not. A dealer maintained W123 with 450k miles may be in better condition than a shadetree hacked W123 with 125k miles.

KBB really isn't a good guide for old cars. An auto appraiser or even looking to eBay for values will give you a better guide on what these cars typically go for.

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Not at all. $2000 should buy a nice car without any major problems, maybe a little rough on the edges. $3500 should look and run good. $5000 should have decent history documentation, less than 250k miles and no significant flaws. Above $5000 should be 100% rust free, include lots of documentation, under 200k miles and need no repairs.

$8,000+ should be near-museum quality with under 100k miles.

Rust takes away value faster than any other inspection point, except when a WVO "conversion" has been installed (That should void the deal entirely).

Thanks a lot. I'm going to go take a look at ebay.

I am a student, but I have been lucky enough to find full-time work for the year and have enough disposable income to invest in ongoing maintenance. Depending on how things go I may not go back for a couple years (I hate being poor and like my job. School was sort of lame anyway; I wasn't learning much).

My understanding of IDI's is that they are much more tolerant of fuels like homemade biodiesel and properly treated and heated WVO than newer commonrail or DI diesels. Please correct me if I am wrong.

That makes sense to me. I think that a lot of these prices are jacked up without merit. A lot of these spendy ads say "good candidate for biodiesel conversion", which is BS; I shouldn't need to convert anything (cept maybe the fuel lines).

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-1991 Ford Ranger: multicolored and the clutch is gonna die.
-WTB w123
-Aspiring Biodiesel homebrewer

I recently bought a 240d off ebay and got a rust bucket. Knew about some superficial rust on the doors but ended up with major floorpan holes. I'd be leary buying one again sight unseen. If I buy again I think I will trying finding a car from someone on this forum. Just a thought, JEFF

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1981 240d aka "The rust bucket"

Good call. I placed a WTB in the buy/sell forum.

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-1991 Ford Ranger: multicolored and the clutch is gonna die.
-WTB w123
-Aspiring Biodiesel homebrewer

I have to say, while I appreciate the general reverence on the forum for these cars, statements like:

...aren't warranted. Buying an older car that can run safely on free fuel in any US weather is a perfectly reasonable strategy. Perhaps you're talking about buying someone else's conversion, since it's hard to know if they've taken care of the car properly. Not a bad point.

But I have an 83 300TD which I had converted by an expert, and I run only on used/filtered veg. Works great and will pay for itself within short order.

Can't we all just get along? Thanks.

$500 http://portland.craigslist.org/mlt/cto/921418984.html

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

That might be a good deal there in Portland. Have it checked out by a reputable mechanic, even if it costs you $100. Cheap insurance.

Mercedes can be very expensive to repair, especially if you have to pay someone else. If you can do some work yourself and ignore some broken things (sunroof, a/c, cruise control you can live without) you will be better off than if you pay a shop and want everything to work.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

If you are going to run biodiesel you will have to replace you rubber fuel lines and maybe tweak with the timing. And as a former college student +1 to everyone who said they can be very expensive if using a mechanic and you will need to find a good mechanic who knows mercedes, DO NOT I repeat DO NOT take an old benz to a mechanic who has not worked on one before. The result might be wrong thing fixed or more things broken and you are out a lot of money.

Thats great for you but a smart buyer will never consider a car thats had WVO/SVO anywhere near it, no matter how great the seller claims their "conversion" is (Especially if its home made/assembled). Coking, gumming of the rings, oil contamination, injection pump damage, hacking of the car for installation, that nasty grease smell everywhere and there is no way to know if the owner had any clue what they were doing when buying and filtering the oil.

The risks associated with buying a preconverted car are far too high to be worth it.

Your point is that it's riskier to buy a car that's pre-converted than one that's not. Fair enough. Mine is just that buying a good W123 and converting it yourself to run veg (or biodiesel, as the poster wants to) is not some kind of sin against the vehicle; it can been done well, and pays dividends, even putting aside the value of learning how Rudolph's engine was meant to be used. ;-)

Even putting aside the fact that these cars use MERCEDES' engines, Dr. Diesel had zero involvement. He died 23 years before Mercedes ever designed their first automotive diesel engine.

This is a valid concern for me. I run VO in my wagon (that I converted) and I'd be leary of buying a car that someone else had already converted and run oil through. Knowing/inspecting the type of conversion and listening to the person talk about how he prepared/ran VO would tell me how much he knows about it and whether he really took care when filtering the oil. Even still, the guy might be an academy award winning actor when selling VO cars, so there's no good way to know if a car has been cared for when running alternative fuels.

What's the easiest way to check gumming/coking of the engine internals? Looking at the injectors? Maybe a boroscope in the injector hole to see the cylinder walls?

To the OP, that $500 300D looks like a good deal if it really starts every time and runs. The non-turbo engine should be easier to maintain, although getting up to speed on the interstate would suffer a little. I'd say keep your eyes open, fair deals pop up from time to time.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

Truth be told I'd avoid an old MB if I didn't have much money. They can cost a lot to fix. You can go months and months and months without any problems then get hit hard when something lets go. So basically find one that someone has taken care of and worked out the bugs on.

If you do a lot of city driving the fuel economy isnt great and diesel is expensive so keep that in mind.

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1985 CA 300D Turbo , 213K mi