So the #1 and #4 injector on my 220D have started to leak. I have looked into new injectors (would do all 4 at once) or would you have them rebuilt to make sure all pressures are close?

Which and why?

Could you define "started to leak" in more precise terms?

I can;t see how injectors that were leak-free would start to leak unless they were torn apart and not lapped correctly or not torqued back together properly.

Every time I've thought my injectors were leaking (even after an injector teardown) it turned out to be failing return lines. Replace these first and see if the leak disappears.

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1981 300TD 310k miles
1970 280sel 172k miles
1966 230 Fintail 162k miles

"Where are we going? And why am I in this hand basket?"

I'd look closely at the rubber injector return lines. Or the nuts on the hard injector lines. The bodies don't usually leak unless someone has had them open and didn't get them put back together properly.

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I will take a picture later to show, I replaced all the return lines in hope that was it. No luck. It seems to be arouns where the injectors seat. They were rebuilt back in 06. It has been a fair amount of miles since than also.

don't know if they have o-rings where the top and bottom of the body screw together, but I had a set where they had disintegrated. Put them on a bench vice, put new o-rings, and snugged them up and put them back in car. Unless you are hearing the nailing, indicating a bad one, I'd just replace 0-rings, snug up, and replace the heat shields or snap gaskets . .. whatever is called for.

Are you seeing pooling at the base where they screw in? That's what my problem was, in addition to needing return lines, and new o-rings for the primer pump!!!!

If all that fail . . . then look at bringing someone else into it to pressure test them, or replace them.

BTW, what's the full description of your auto? year, model, engine?

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1983 300D, the "Avocado"
1976 240D, 4-spd the "Pumpkin", SOLD to Pierre
1984 190D, 2.2L, 5-spd, my intro to MBZ diesels, crashed into in 2002

If I remember correctly, your 220D is a '70 model. Does it not have an all metal banjo bolts and metal tubing return system until the one rubber connection toward the filter? If that is the case, there is only a very small likelyhood that any of that metal system just started leaking. The rubber leaking should not appear to show up as an injector leak, since it is so far away. Could well be the injector to block or PC chamber joint.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

I did the return lines, I have a little nailing happening. I have been so busy I don't get home in sunlight hours and I have no garage. I will find out soon.

1971 220 Diesel.

I will look at what style.