Trying to buy an old Mercedes Diesel and everyone's telling me not to

[maiyaa]

I've been trying for the last three months or so to find a decent Mercedes Diesel on CL. I think I've found a few but everyone including the mechanic I bring the cars to says it's a terrible idea. Aside from the fact that they're very sexy looking cars I thought there was a huge community of people that were seriously enthusiastic about the old diesels. Now everyone around me is wondering what the hell I'm doing. Can anyone set the record straight or is looking for an old diesel really that bad of an idea?

For clarity I've been looking at 240D and 300D from 70s through mid 80s. I realize that an old car is going to come with some baggage, but this much?

Thanks

[martureo]

I bought mine after I totaled a car in the snow. Finally got the right moment to have the cash and the need for the car. Almost everyone in my family thought it was a bad idea and advised against it, but I've driven it daily for 14 years now without too much trouble.

You'll have to decide to become involved or have deep pockets and a friendly mechanic. That's the least of your worries.

1. Check for rust. If there's any of it then there's more you haven't seen.
2. Check the engine cold and see how long it takes to start. These engines last forever, but if they've been neglected or abused then move on to another example. Rebuilds are not common and are decently expensive.
3. Check the blowby of the engine while you're at it. Unscrew the oil cap while its running and see if the cap dances or tries to launch itself.

Outside of those and a few other items that others will recommend, go for it.

[tyl604]

I think you are on the right track. You will not find a better "new" one in terms of quality, ease to mechanic, and longevity. They are absolutely the greatest. And easy and fun to maintain.

[engatwork]

You don't say what part of the world you live in but the a/c systems can be an issue if you live in areas of high temp and humidity.

[barry12345]

Doing repair and maintenace yourself. Decent car to do it on as well. Intent to pay others today to do it. Probably not the best ideal.

Same rules apply to many far more modern brands. Except many are far more difficult to deal with issues they can develop.

Maintain one of these cars yourself. You are far less likely to get ripped off in the future. By unethical repair shops.

[Phil_F_NM]

If you're in the Philadelphia, PA area, swing by and I'll show you what to look for in a W115 and can speak at length about W123s. Disclaimer: I have my own beloved rusty Benz up for sale, but I'm all for showing a prospective buyer where to look for rust, what to look for in the engine bay, etc.

Warning: Once you get an old diesel Benz, you may want another, and another.

Phil Forrest

[cth350]

if this is your second car and you can live with it being down for a week every now and then, it's not an unreasonable decision.

After you decide that you can handle the work (or not) and that you can live with "patina" (which is old car speak for "imperfections"), you may need to start shopping for a mechanic who will support the car. Let those others deal with the more pedestrian things you've got. Your benz diesel will need better folks to support them.

If you share your general location, I'm sure somebody here can suggest a local resource.

-CTH

[cmac2012]

I have two, I like them all at all, but there are issues.

The pithiest criticism I have, well, i’ll put it the way I said it to what are the guys at Napa auto parts, I got an oil filter on the road from them, not my usual go to place for parts:

“The dirty little secret about Mercedes diesels is that yes, the engines do run practically forever, but everything else breaks like any other car.”

He filled in the rest saying something like and a lot of that stuff is going out of production. Some truth to that, radiators were hard to get as in impossible for my SDL but then someone started making them, all aluminum, in China, I have one in my SDL, works really well.

But it is still an interesting adventure.

[Graham]

Well those diesels are getting old and need work on the usual things. Rust is always a problem and depends on where you live.

Finding a pristine car will not be easy. I bought my 85 300D about 30 years ago when it had done about 80k miles. Had the rusted fenders edges repaired, new belts and brakes. Despite having other cars, I still drive the 300D almost every day and it has now done 285k miles. Spent a lot on maintenance, but nothing like the depreciation costs on a newer car.

[my83300cd]

I drove my dad's 83 300cd from 254k miles to 375k miles, had the front end rebuilt when I got it in 98. The engine is now in a Toyota 4x4. The CD floor rotted out. Got a 199E 5 speed for less than 1k, put in a water pump and 2 radiators, and both my boys learned to drive on it. They called it the hummingbird due to the rusted out exhaust. Picked up a 77 300d, 1k, ands its cost me tires, brakes, a starter, and an exhaust system. I've put 20 k miles on it and flog it as my daily station car. No ac, no cruise, buy what do you expect for a grand?
Given I live in CT, rust is an issue...that I won't Subject my bus, bug, or midget to.
Get a diesel from a rust free location, maintain it, and stock up on a few parts cars....

[Idle]

I would like to add a comment for others to comment on.....

These 123 diesels usually have oil seeping across the valve cover from the filler cap. Everyone will tell you this is normal. It's not and they didn't do that when they were new.

I was once told this is the sure sign of a stretched timing chain. The car still ran great, got 31 mpg and road very nice so changing the chain at that point was not critical.

So.... Is this the cause of the blow by?

ALSO: Sometime the transmission seems to slip when changing from second to third. I have always found this to be a bad modulator valve on the transmission. And these are cheap so don't panic if your transmission starts to slip. DO have it checked out but also expect it to be the modulator.

[benjamin110]

just find a nice car the one I had ran well