a grease-eating 1972 Mercedes-Benz 220D!
How'd this happen? Am I crazy? Isn't one old weird diesel enough?!
Most of you know that Libby and I have been slowly moving toward owning a car that can run on waste vegetable oil (abbreviated WVO). That's why we bought our '82 Audi almost a year ago. I've done a bunch of things with the Audi since then but have not yet converted it to run on grease. Right now I'm trying to save it from destroying itself via what's likely is a broken valve spring. (I think I've pretty well narrowed that down now... we'll see when I have a broken spring in hand.) So after going without a vehicle for the last month I decided to look on Craig's List for a second vehicle. Not that we'd be a "two car family," but that we'd not be without something to drive during my frequent tinkerings.
I searched for used diesel sedans under $3000 thinking that I'd find another old VW or something. Instead I come up with this Mercedes on the top of the list. It was the only diesel Mercedes I'd ever seen in our meager price range, and it already had the Greasecar WVO conversion kit installed on it (a $1000 value, labor aside).
Still, I was skeptical. In fact, I didn't even think much of it at first. Sure, I know that Mercedes is what most greasers shoot for. Sure, I've known someone who drove a '70's Mercedes diesel with over 500,000 on the clock. But aren't parts going to be impossible to find and more impossible to pay for? And anyway, who buys a car from the '70's that they actually intend to drive?
Libby was excited, though. So I decided to go take a look. It drove pretty well, had more power than the Audi, and had no noticeable difference running on grease compared to diesel. The only thing that felt a little odd were the brakes, which worked fine if you just applied a little more pressure that one's used to doing today. In truth, the brakes felt like they do on my '73 Beetle.
Next came the agony. I agonise sometimes about buying a pen. You can imagine how much worse this was. I did some research to soothe myself. I looked at autopartswarehouse.com to see just how expensive and rare these parts are. To my great surprise, they weren't bad at all! Just look at that long list of parts available.
As I happened to be thinking about the Mercedes vs. VW issue one morning, it occurred to me how much more well suited for grease the Mercedes is. It's all in the diesel injection pump. The VW Bosch pump (which I disassembled last fall and should have gotten a picture of all the tiny little intricate parts!) has nothing more that the fuel itself to lubricate it's precision machinery. This old Mercedes pump (which I remember seeing on an historical time line in a Bosch textbook) has its own dedicated oil supply and is in general much simpler and less dependent on the exact fluid qualities of what's going through it.
After these two considerations were taken care of, I bought it. I still feel a little crazy, but here's some pictures:
Above is the 15 gal. grease tank in the trunk. It's high-tech, but you can't tell because it's covered in insulation - a nice touch from the previous owner. The key to the grease system is keeping the vegetable oil hot.
These are the grease controls. On the left is a gage that gives you line pressure before the injector pump. That way you know everything's flowing OK. The other gage is fuel level in the grease tank. In the middle is the three way switch for Veggie, Diesel, or Purge. You start on diesel until the engine reaches operating temperature, switch to veggie for the duration of your ride, and purge the system with diesel before shutting off the engine.
My current main concern after buying the car is the fact that it consumes a certain amount of oil. I haven't driven it enough to know just how much. The previous owner said he added about every 6 weeks. One reason why this didn't deter me more is that my Audi owners manual states that some oil consumption is expected from the diesel. The Mercedes manual apparently says the same thing. Here's a discussion about it I found today.
Aside from the mechanical stuff, I like driving it. The interior is mint, and since you can't see any of the rust spots from the inside, it feels like luxury. Plus, it smells a little like my dad's 1956 Buick Special. Maybe that has to do with what the dash and seats are made of, I don't know, but it's a good association.
All I need now is a source for grease and a filtration system.