Old Mercedes diesel cars

I just got a 1982 Mercedes 240D. Anyone else here own and/or know much about these cars? I’m interested in learning what some common problems and quirks are, and what resources I should be aware of. I’ve already found mercedessource.com but that’s about it.

Here’s mine. Just bought it from my uncle in southern California, who bought it new. I spent the past 3 days driving it to Alabama. It now has 237,000 miles on the odometer but still running fine.

The only problem so far is that sometimes, when I shut down the engine, it won’t restart until it cools down. I hear the click but no cranking. I’ll take it to a shop soon - I’m guessing it needs a new starter or solenoid?

It could be the starter spacing — that it is too close to the flywheel to engage it properly when hot (but once it cools down it is able to do so). Had that problem on an old Pontiac. A small shim on the mount side of the starter motor can cure this.

Can’t offer much advice on the car (other than it looks to be in excellent condition), just curious what route you ended up taking. I didn’t see the route thread until it was too late.

Sorry, I’d been meaning to thank everyone who responded on that thread. I ended up taking I-10/I-20 as you suggested (IIRC), figuring I’d be better off avoiding larger cities because of the limited time. Yes, it was boring but it was a smooth drive.

I had a bit of a scare with that starter problem somewhere in Texas - stopped for gas and wouldn’t start. Pushed it across the road to an auto parts store, waited for an hour for a mechanic, decided to try again and it started. I only stopped the engine once after that (overnight).

You’ve got a great car there that, if given some love, will last at least another 20 years.

The 82-85 Mercedes diesels are popular for straight vegetable oil conversions because they use 5-cylinder indirect injection engines. I think they also use sleeved cylinders, so you can replace the sleeve when it wears down.

The electrical system may give you some problems - notably behind the dashboard. It’s common to find them not displaying speed or engine RPMs at all. And the A/C system may give you fits if one or more relays aren’t working quite right.

These cars have mechanical fuel pumps, but they are not self-priming. There’s a priming pump on the incoming fuel line that you can use to pump the air out, should you get a bubble or run the tank dry.

Have the cylinder compression checked - spec for new is about 350 PSI, IIRC. All five cylinders should be close together - if the first cylinder is much lower than the others, you’re going to have starting problems sooner or later.

Oddly enough, for being both a diesel and an automatic transmission, your car can be tow-started. There are instructions in the manual for doing this.

I concur with AHunter3, it’s probably not the starter itself if you’re hearing the click, have the spacing checked.

If the vacuum system is leaking, certain accessories won’t work. Cruise control, A/C, door locks, fuel door release, and stop rod actuator are all run off the vac system. There’s a seperate vac unit for the rear of the car. The stop rod actuator is the important one - if the vac system leaks enough, it won’t stop the engine and you’ll have to do it manually. There’s a tab under the hood marked “STOP” - press it sometime the engine is running . :smiley:

The most common problem I’ve heard of in these cars is transmission slip. The biggest danger is overheating the engine.

Keep your fluid levels topped up, and you’ll be driving that car out past 1 million miles. Write to Mercedes-Benz in Germany every 250,000 km, they’ll give you a badge for the front grill. :slight_smile:
-SteelWolf, owner of a 1983 300SD and a 1984 300SD (only one of which works)

Oh, one thing I forgot - replacement parts can be expensive, so if you can find a wrecked one with a good engine/transmission, buy it and cannibalize as needed.

Thanks Basandre. Turns out one guy I know at work has an '80 300D with the vegetable oil conversion, and he’s trying to talk me into it.

I didn’t realize the door locks are vacuum-operated! That explains why they stop working after the car’s been parked for a few hours. (They work fine as soon as I start the engine, so it’s no big deal.) Cruise control doesn’t work either, but the AC seems to work fine. (At least when the car is running - it doesn’t seem to work well when idling. Again, no big deal, unless it’s indicative of impending or underlying problem?)

I’ll get the starter spacing and compression checked.

Didn’t know that the rear pump autos still existed. Former owner of a '62 220 SEb and a '63 300 SE, I’d learned the ‘coast down a hill at 10-15 MPH in neutral and then drop into drive’ for starting. :smiley: