I recently bought a 1972 220D. When the owner showed me the car, it idled rough. It had been sitting for a year or two, so I drained the fuel tank, replaced the rubber hoses and fuel filters, did an oil change, cleaned out the intake, etc.

Since doing this tuneup, it still idles rough. I've bled the fuel system the best I can. Usually I can get it to idle for 5-10 minutes, then it suddenly stalls and won't start up again for an hour or two, which I find strange. Once it starts up again, it does the same thing.

The part that worries me most is the noise that it makes when I rev it. It almost sound like a rod knock or something internal gone wrong. I did an oil change, and the oil is full, but the oil pressure gauge appears to be broken, because it reads 30psi all of the time, even when the engine isn't running.

I have a video of it running. Let me know what you guys think.

1972 220d running - YouTube