Can a 300,000 mile diesel be dependable?

[93defender]

OK, I'm thinking about trying the diesel thing out and wanted some thoughts. Found a late 80's 300D that has good history. Looks good drives good. Has 300,000 on the clock though. I know these engines are bullet-proof, but what about everything else? Can I throw the wife and kids in it without worrying? What are some things that I should expect to go out before long? Car has a good maintenance history without that long grocery list of "new parts". Is it typical for the tranny to be dead by now? I don't mind working on stuff that is good quality. I am currently driving a Honda.

[Jeremy5848]

Welcome to the forum. I hope we can be of some help.

This car you've found, you can depend upon it to be a diesel. Everything else is problematic depending on the quality and quantity of care that the car has received in the past and your expertise with a wrench. We take my wife's '96 diesel with 262,000 miles on the road all the time with nary a worry but then again, it came with a complete service history and I have kept it up.

It also depends on what kind of "late 80s" 300D you have found. If you stick around long enough to learn about the "rod-bender engine," for example, you will want to revise your opinion of "bulletproof."

Transmichigans generally will need work at or before 300,000 miles. Depending on the year/model, the car may have "environmentally friendly" insulation in its wiring. Unfortunately, such stuff turns into fragments after 20 years or so. There are many other things to looks for. Please let us know more about what you've found.

Jeremy

[93defender]

Thanks! I'll expand on what I have found. It is 87 300d. Has the original engine, and I think the original head with 300,000 miles. Guy has complete history. Never wrecked, always in the south. He has had it for about 3 years. I found he has quite a few posts on this site regarding the car. Isn't hiding anything and claims to drive it on long trips without an issue. I think the car is nice and legit as of right now. What I'm concerned about is will it morph into the "problematic Cadillac" where I'm spending time and throwing money at the "rolling dead". Your thoughts?

[Brian Carlton]

Although the consensus from the layman is that the engine is "bulletproof", in reality, most of them will give 350K-400K before some serious work is required. This presumes that they were well cared for with proper oil changes throughout their lives.

There are many components within the engine that require some expensive service at that mileage level and, generally, it's not worth the effort due to the wear on the bottom end.

I would not purchase such a vehicle and begin to spend significant repair money on it.

[pj67coll]

I would say that an 87 300D which is a W124, while a good car, is less "bullet proof" than an earlier simpler vehicle. I had an 82 240D which I bought at 372K miles. It's engine certainly seemed "bullet proof" and it took me to almost 400K before I made the mistake of junking it for reasons that had nothing to do with the engine. However that was an older OM616 which I believe was an all iron unit. No aluminum head etc. There were however issues besides the engine that were problematic. The A/C for example. And the clutch and manual transmission which were completely original and which I'd sort of messed up trying to repair. Which is why I got rid of it. I guess what I'm trying to say is that no matter how inherently good a vehicle may be, and there are none in my opinion as good as an older Benz, you cannot expect any piece of machinery with that age and mileage to be without issues.

- Peter.

[H-townbenzoboy]

It all depends on how the previous owner maintained the vehicle. If they maintained it so it could be ready for long trips at a moment's notice, then it's likely alright. If past maintenance has been spotty, unknown, or just enough to get by, I wouldn't take it out on the highway until all of those things have been sorted out. After things were sorted out I would take it out on the highway by my self on the first few journeys to test it so if some failure happened, I wouldn't have pissed off kids and a wife to deal with. If you have to make a family trip, I believe that the best bet is to rent something.

[Edward Wyatt]

IMHO, even a diesel Mercedes will be worn out with that kind of mileage. If you buy it cheap as a toy to tinker with it will probably be ok, but if you drive a Honda you won't be happy with a 300k mile Mercedes.

I learned the hard way, these old diesels will run a long time, but they slowly wear out around the motor and the parts cost just as much as newer Mercedes parts.

I have owned several W123 and W126 diesels, great cars back in the day. Today the average example won't make a good daily driver, unless you are hard core diy mechanic and you have a backup car to drive.

Plus, the climate control systems on these cars are horrible, you will sweat even if it works. Remember the R12 Freon used in the system is hard to get and expensive(for most people).

[Jeremy5848]

It's very hard to find a used car that doesn't need something expensive now. It's therefore almost impossible to find a used car with 300,000 miles that won't need something expensive in the next few (1,000? 50,000?) miles. Even a Mercedes wears out and they are definitely expensive to repair -- especially the OM603 engine in your '87 300D. With fewer miles (150,000--200,000) it would be much less risky. If it was a case of using it only to run around town, sure, we'd say "go for it" (depending on the price, of course). However, as a long-distance car for the family, there are too many expensive things getting ready to wear out (timing chain, IP, transmission, etc.) and all the time the main and rod bearings and the rings are getting weaker and weaker. Since you can still find nice examples with a lot fewer miles, I'd suggest waiting.

[Diesel911]

You can easily answer your question by reading a bunch of threads and taking note of the milage on the cars and the type of problems people are having.

Any used car is problematic. With Mercedes unless you can do your own work the repair cost can soar suddenly.

I sure hope they are since I drove my last 240D, (an 84 model Euro) all over five states, relying on it to be at appointments on time in order to make a living. The car was faithful up to 450,000 miles when I put my son in it at the age of 16.

The car gave me a few very minor schedule changing events during that time that were easily overcome.

[ImBroke]

It all depends. I"ve taken my 330k mile car to a Maryland GTG, which was about 200 miles away. I"ve brought my 280k car to Maryland a few times, and other places. I just maintain them to where I think they will perform correctly, and they do. Everything can break down, as in my Honda last week on the way to work. Crapped it's second electric fuel pump. So, I'd say it's a crapshoot no matter what car you drive.

[okyoureabeast]

This thread put a smile and fear in me at the same time.

I drive an 85 300D with 331,000 miles. I just put about 1000 miles on it. So far no problems. I have a great indy mechanic that works exclusivly on diesel engines. He showed me a bunch of things that could give me problems and prioritized the repairs. Needless to say I did everything he suggested.

I have AAA, a tool kit, and a cell phone. Hopefully I won't ever need any of them.

[mobetta]

I've got 329K on mine, drive it every day, just returned from a 2K RT to the black hills and other parts west w/ the family of four.

but I've had it for 60K+ and replaced many parts in that time, and I am very familiar with the car, do all my own work, etc.....

I've only been towed home once, when a brake rotor blew apart on me. never had a problem w/ the engine or transmission. yet.

but this is a 123 car with the cast iron 617 engine.

[zeke]

Originally Posted by okyoureabeast

I have AAA, a tool kit, and a cell phone. Hopefully I won't ever need any of them.

x2. Wife and kids drive around in a 250k 300TD every day and I commute to work in a 250k 240D every day. They are the only two cars we have owned for about 2 years.

I have only taken my 240D to a shop once to have the alignment done. Everything else I have done myself, though I will probably be taking the 240 to an indy in the next year to have the timing chain replaced.

Solid, reliable cars if you have the time, inclination, and space to DIY

[barry123400]

It is hard to really depend on any really older car as your primary transportation. There are just greater risks with higher milage and age. If this were not so people would not buy replacement new vehicles from time to time. This to me is just common sense.

That said older cars can be very enjoyable as well. Most the cars we own of this brand are caught between being older cars and antiques.

The power trains will usually give adaquate warnings of impending failures. You must be prepared when required to do the vast majority of repairs yourself to save your wallet.