Looking for info on Mercedes diesel engines...

For what it's worth, my '85 300SD (same driveline as the D) has better than

225,000 miles on it now and has no problems whatsoever with the engine; in three years I've had no problems, and there's no indication that the previous owners ever did, either. The 5-cylinder 3.0L Mercedes turbodiesel is renowned for its longevity, as long as basic maintenance (oil changes, valve adjustment) is kept up. With recently-replaced glow plugs, mine still fires up immediately in winter. If I had to guess what problems I might expect in the next hundred thousand miles, engine trouble would probably be the absolute last on my (very short) list.

I don't know what effect vegetable oil has on an engine's reliability, though it's probably negligible. I have heard of Mercedes diesels that have been converted and run fine.

Excellent. I'm nervous about buying a high-mileage used car, even a quality Mercedes[1].

I've been told that Mercedes maintenance and service can be rather pricey, particularly with older vehicles. Is this the case?

Agreed. I doubt it has any sort of negligible effect. It'd sure be nice to drive on practically free fuel, while being able to switch to regular petrodiesel when on long roadtrips away from the dispenser at home.

With 248k miles on the Mercedes odometer already, do you think it'd be worthwhile to sell my 2003 Honda to purchase it? I've been doing a lot of reading at Edmunds.com, and I'm not entirely convinced it's a good idea.

Now, if it only had

You don't state if this is a turbodiesel (120 HP) or not (77 HP). Buy only a turbodiesel, same fuel use.

The five cylinder diesel that you want to buy is a very tough and durable all cast iron engine. That said, given normal maintenance it should go 250K - 275K miles +/- 10%. Given very good maintenance 300K etc.

However, by now this car has been owned by X number of people, some of them were good to it others perhaps not, so it's incumbent on YOU, for its your money that's at risk, to have an independent M-B shop verify the engine's actual condition with a compression test. That's the ONLY diagnostic test that will tell you its internal condition (short of taking it apart). This will cost about $100 (request an estimate) but then you'll know if the motor has many miles remaining, or not. And if not then you'll be happy to have limited your expenditure on this car to $100.

Rebuilt engines are available for $3,000 - $3,500 but realistically few twenty year old cars merit that cost so a used engine ($800 - $900 + installation) is the usual alternative.

Don't get too excited about saving money on fuel, the 24 mpg economy doesn't offset repair costs. This will only work as an economy car if YOU do all the maintenance and most of the repairs. If ownership and running cost govern and fixing cars isn't for you then buy a high volume car that any local garage knows how to fix.

It's the turbodiesel model.

Hmm. Considering it already has 248k miles on the clock, that doesn't sound very good.

I was under the impression that Mercedes diesel engines had significantly longer lifespans than what you quoted above, assuming proper service.

Agreed. I happen to have a most excellent mechanic shop that specializes in Volvos, BMWs, and Mercedes. They offer pre-purchase inspections for $125. When I owned a Volvo, I had it serviced there for 13 years. They are trustworthy.

Would a thorough inspection by a well-qualified shop be able to accurately (within reason) estimate the lifespan of the car? You know, like "Oh, your engine has about 150k left in it, your interior looks great, and all the wires and vacuum hoses should last for the foreseeable future...".

Hmm. Something to keep in mind, thanks.

I have a Honda Insight (two-door hatchback hybrid) that I rather like, except I'm looking for a vehicle with a back seat, sizeable trunk, and is more rugged/durable. Diesel-powered is preferred, due to the ability to run on biodiesel and vegetable oil.

Assuming the car is in good shape, and I will hopefully be inspecting it shortly, my main worry would be the drivetrain (engine, transmission, etc.). If the engine is nearing the end of its service life, that could be a problem. Similarly, if parts of the car start breaking or malfunctioning, that could also be an issue.

I don't mind turning wrenches every now and again to fix something...but the Mercedes /was/ designed as a luxury car. With regular service (i.e. oil changes, fuel filter changes, etc.), I would hope that it would last pretty much indefinitely in terms of most interior parts not associated with the engine. Sure, a speedometer cable might wear out, and I can easily replace that. But if I need a new engine, a new transmission, new headliner, new instrument panel, etc., that would definitely not be worth it.

Let us assume for a moment that the vehicle is in good working order. No repairs are necessary, and all that's needed is the standard regularly service at pre-scheduled intervals. What's a ballpark figure for these costs? I take my Honda in for an oil change every 3,000 miles at the local dealer (they have good pricing on service), and it costs me about $40. Regularly scheduled maintenance (i.e. 5k, 15k, 30k, etc.) costs a few hundred bucks or so (no more than $300-$400, so far). This is for a car with 20,300 miles on it. Do you have any idea what I would expect for the Mercedes, assuming that there's no major repairs necessary?

Having a vegetable oil/biodiesel-fueled vehicle would cut down significantly on my fuel costs, which, even with a hybrid, are the biggest costs I incur with my vehicle. Assuming regularly scheduled service is able to keep it in good working order, I should actually be able to save money over my current car. However, if things start falling off, or the engine wears out, etc...that could be a major issue for me, and I'd stick with the Insight, small trunk and all.

Thanks for your help -- I'm looking to make an educated, informed decision and am consulting sources ranging from Edmunds.com, to this group, to several diesel-savvy friends I have. Your knowledge and experience is extremely helpful.

248K IS a lot (mine has over 300K). You have to include other factors, such as the condition of the transaxle, transmission, all the other mechanical bits and pieces. There are many excellent cars out there with much less mileage, don't hurry, find a good one that has been WELL maintained. Make sure you get one that has no oil loss. MAKE SURE that the transmission fluid level is proper.

Any badly maintained car will be pricey. If old benzes were costly to maintain most of the people on this board (including myself) wouldn't be driving them. We have 5 benz diesels in our family and we're definitely happy with them.

BAD idea. 248K is too much. Look for another one, check out ebay for nearby cars.

It's NOT a good idea. 248K is too much to buy.

Aren't you going to lose a lot of money selling it?

They are that reliable. My friend has a 1958 that he uses for daily driving. :-)

cp

Aside from the engine,do an inspection throughout the entire vehicle for rust.You did not specify if this is a W123 or a W124 but if a W123,pay close attention to the floorboard(lift carpet up)especially at the accelerator pedal and the seat base.In the trunk,look in the side pockets and underneath that section also,plus the rear wheel arches and mounting area of rear bumper.When you open the doors,look at the underside of door and where the seatbelt fastens to the pillar.Hope I didn't scare you on W123's forever but thought I would add.

The thought I'd raise isn't with longevity. Several friends over the years have taken their MB diesels well into the 400k range. Even if this one would do that well, subtraction will tell you more. You've got probably 125K left. That's not a lot. Here in Columbus someone this week is selling a '91 350SD for $13K with

a little over 100K miles. That would be a nice diesel to start with.

Collin

The car has 248K miles on it, which is at least in the range of the typical lifespan. Unless the rest of the car is in pristine condition and you are prepared to spend $4000 to have a rebuilt engine installed, I would walk. You also have to be prepared to deal with lots of the other components that you can expect to go at this mileage and age. Things like vacuum hose connectors and actuators, window seals, etc. Some of these are dependent on age, as well as miles, as plastic/rubber deteriorates over time. Many of these smaller things don't cost that much to fix, if you do the work yourself. However, if you're selling a

2 year old car to buy this one, this would likely be more aggravation than you are prepared to deal with.

Surprisingly, no.

This is the Bay Area, and there's a large market for hybrid vehicles. Many people use them as some sort of political statement.

I bought it at $20k-and-change in '03. I got an offer for $15k the other day. With about $6k of bodywork put into it[1], it would seem that I would come out slightly ahead. Even without the bodywork, I'm rather surprised that a low-volume, never-very-popular car hasn't depreciated far more than that.

2000-2002 Insights are selling on eBayMotors for about $10k, and they have ~100k miles. This only has 20.5k, which is quite good.

Getting back to the Mercedes, I'm curious...on one hand, you say that "they /are/ that reliable", yet also say that "248k is too much to buy". How does that work?

Unfortunately, late-80s/early-90s 300D series vehicles with less than $100k miles do not seem to exist, at least not on Craigslist, which has numerous ones locally. Many of them have in excess of 200k miles. That's what's in my budget, and the years when Mercedes seems to have made Good Diesel Engines. Newer ones are much too expensive for me, and there are several years where the number of diesels produced was rather low.

[1] Again, the body is rather...delicate.

I've owned a 1980 300SD since new; it now has gone 109K miles. I keep it garaged and in top condition. It's a great car for local use; we use a newer, smoother, quieter and more powerful car for trips.

The diesel's repair and maintenance cost approximately equals its fuel cost: 8 or 9 cents (now probably 11 cents) per mile, insurance excluded. I do the valve adjustments and small repairs, a shop does the oil changes and any major work. That's its long term economics.

In reading your posts, it would be a big mistake to trade off a two year old car for a twenty year old car, IMHO. I say that despite my owing a

25 year old car, but mine was bought new and I know it well so there are no buyer's surprises hidden away somewhere.

Indeed. Hopefully by running on free waste vegetable oil, I should be able to cut expenses even more.

I don't mind doing work like that on the car (leaving the oil and major work to the shop), in fact, I'd rather like it. :)

I agree. That doesn't make much sense.

I'm going down today to examine and possibly test-drive a 1992 300D, which has 198k miles. According to the owner, it's in good-plus condition. Obviously, a thorough examination will determine if that's the case.

While perhaps selling a 2-year-old car for a 20-year-old car isn't the wisest of choice, selling it for a 13-year-old-car would be a bit better. About 50k less mileage, less wear-and-tear on the car, etc. Probably a better AC too.

There's another car, an '87 300D with only 119k miles which might also be something to consider. Same price as the '92, though I may be able to negotiate a bit on both vehicles -- they're asking double the Blue Book private-party price.

The guy selling the '83 veggie-oil car also does conversions for a living. I inquired as to the cost of converting the engine to veggie-oil (it can, of course, burn regular diesel as well) and what the cost of a home filtering/fueling station would be. It would be a far better choice to get a better vehicle with fewer miles on it and do the conversion than get an older, more worn vehicle with the conversion kit already installed.

And I certainly wouldn't feel uncomfortable selling my 20,500 mile Insight for a 119k Mercedes. 250k, that's a bit much. 198k...I'm not sure. Depends on the rest of the vehicle and a thorough inspection.

Amazingly enough, I just got an offer for $16k for the Insight, which is excellent. We'll see. :)

I believe the '87 300D has a six cylinder 148 HP turbo diesel. Nice engine, smoother than the older five cylinder engine BUT cannot be overheated. This engine has hydraulic valve compensation so there's no valve adjustment requirement.

This '87 may be something to look at seriously due to its relatively low mileage. If you buy it be sure to maintain its cooling system well.

Not many '87 diesels were sold.

Not to "rain on your parade" but do you really want the mess and smell of diesel fuel and oil etc. in your garage?

Go to any diesel pump and drip a few drops onto your hand - and then try to get it off. Like a skunk odor, IMHO.

Good thing to know. How does it compare in terms of horsepower and torque?

What about early 90's (1990 to, say, 1992) diesels? How do they compare? Still have the tank-like feeling?

*nods* Proper service will, of course, be done as recommended by the manual and mechanic.

I'm also thinking of doing the GreaseCar.com veggie-oil kit, probably doing it myself.

Indeed. That's what the seller claims, using it to justify their double-blue-book-value asking price.

It would be helpful to state clearly what you are talking about:

W123 300D W123 300D Turbodiesel W124 300D W124 300D Turbodiesel

because they have different engines and different bodies.

This is a W123

and this is a W124

(European headlights)

Juergen

Hopefully I wouldn't be doing much with actual diesel fuel in the garage. More like work with vegetable oil. I'm hoping to make an arrangement with a local diner (that I'm a moderately frequent customer at) to have them set aside some oil every week for me into a plastic oil drum.

Hopefully the filtering/fueling system at home would be a sealed system, so I just need to bring the drum back home (and leave an empty one there for the diner), let it settle, filter it, and pump it into the "ready to fuel" drum. I'd strive to have it work with practically no open containers, so the risk of spilling would hopefully be low.

I think I'll pass. :)

It would appear to be the W123 300D Turbodiesel.

My apologies, I did not know there were different models of the 300D for a particular year, other than with/without the turbo.

248K is too much too buy because of potential work to be done. Of course, if you're getting it dirt cheap then definitely get it. Once a benz is "stabilized", everything done, it will keep on going. Other cars just fall apart. Not all of course.

If they're cheap then it's worth it but find out what has to be done, look for affordable mechanics, get everything done and the car will be fine.

From what I hears whenever I'm in Europe, they're still excellent. Though there have been issues of course. My uncle has a Sprinter which he uses to deliver produce, couldn't be happier with it.

If you can get it cheap and fixed inexpensively then it's worth it.

Here's some good advice; go on some local forums and search out other benz fanatics and ask them for any good, reasonable mechanics, there will definitely be some around.

And another piece of advice; do NOT take the car (if you buy it) to a dealer unless as a last resort. It's ridiculous how many people bring old benzes to the benz dealer and then complain what a ripoff benzes are.

cp

'91 350SD? Best NOT to touch it unless the engine has been replaced or fixed.