Hello, all

Apologies in advance for the long, seemingly rambling post. I'm just trying to include as much relevant info as I can off the top of my head.

Some of you may be familiar with my project - a 1982 240D 4-speed. I bought the car in 2012 and was working on it until recently. I got it on the road, finally, on Sunday 10/18/2015.

Right now, the car's got 275,XXX miles on it. The car ran and drove VERY nicely until Monday of this week (so, for a week), when it started running roughly for no discernable reason - at idle. It seems to run OK when I drive it (took it for a test spin tonight).

Right now, I'm battling a few issues. I know the battery needs to be replaced, but I don't want to go ahead and do that until I have it running correctly again.

All the fuel lines (including the injector return lines) and the fuel filters are freshly-replaced (less than 2 weeks ago). I did a diesel purge just before driving the car on 10/18. This also includes the fuel tank screen. The tank itself - I cleaned it out last year while working on the project. In addition, I installed a

When I started driving the car, I had maybe 7-10 gallons of diesel in the tank - all bought from a Sunoco station. I brought it home in jerry cans and added it to the clean tank. I've driven the car maybe 200 miles locally so far, and filled up the car this past Sunday at the local Sam's Club. I added some Power Service Diesel Kleen to the tank, just to be sure.

The rough running happened right after the car's very first highway run. On Monday night, after driving the car locally for a week, including my 13 mile (each way) commute to work (top speed apx 50 MPH during commute), I decided to take the highway home. So, I had the car up to 65. It seemed to run, drive, and handle well. But, when I got off at my exit, I noticed the car was running rough. The timing of the highway run and rough running may have been coincidental, but I don't know for sure.

The car doesn't seem noticeably low on power, but I can't be sure.

When checking under the hood, I noticed that there was a slight fuel leak from the fuel filter banjo bolt (the big can filter). I'd neglected to replace the crush washer when I replaced the filter (I know, I know...). Thinking I was sucking air in from this point, and that it was a potential cause of the rough running, I decided to replace it.

I didn't have one on hand, so I ran to the store to get one. The only one I could find was a copper washer, as opposed to the original aluminum one. I replaced it along with the rubber seal ring on the banjo bolt (amazingly, I had a few of these new on hand). The car seemed to run a little better, but still not perfect. I took it for a drive around the neighborhood, and it seemed to run more or less OK. When I got home, I checked and the bolt was still leaking. I'm not getting a good seal with the new sealing washer, so I'll have to remove it and try to find another washer that fits and seals.

So, that may still be the problem. But, if I seal that leak and the car still runs rough, what's the next step for diagnosing the car?

The car has a new thermostat and temperature is holding steady at just below the 100 mark (the mark between 80 and 120), so I don't suspect a head gasket issue. The car also has a fresh valve adjustment - a couple of weeks back, just before I started driving the car.

I doubt a 15 minute highway run at 65 MPH in 4th gear was enough to cause any damage to a car that was running very well just a day before. It's odd that the engine's behavior changed so dramatically and so suddenly.

I'll try to get a new crush washer in there on Saturday and fix the fuel leak. If that doesn't help, I'll have to continue on with diagnostics. The car still starts very quickly, so I also don't suspect any sort of compression problem. If this minor fuel leak isn't the issue, I'm wondering what to look at next. Injectors? How would I diagnose bad injectors? Could one go wonky so suddenly?


Thankfully, I have other cars to fall back on while I sort this out. As I said, this 240D is still very much in shakedown.