I have a 1982 300sd that has a leak at the base of the injecter.I was told the place where it is leaking is called the cup.It looks like it is leaking between the casting and the piece called the cup.It does not look like it is leaking at the base of the injecter.Is anyone familiar with removing the cup and how is it sealed in the head? thanks.

More likely you just need to replace the cloth braided return lines.

thanks for replying but thats not were it is leaking.

Finding the leak can be tricky. If you haven't installed new lines in some time, do so, see what happens. Cheapest, easiest. Usually the injectors don't just start to leak.
Good luck.

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83 SD

84 CD

Mine were leaking at the base and I merely tightened the bottom ring a couple of wacks and that took care of that - that is of course after I replaced the return lines.

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Peach Parts W124.128 User Group.

80 280SL
85 300SD
87 300TD
92 300D 2.5 Turbo
92 300TE 4Matic

If this was your injector would it be leaking around the middle between the upper gold colored part and the black injector nut (cup?)?


If it is leaking in the middle sometimes re-torquing the injector nut to body will stop the leak. If not you are having another problem like a hair line crack in the injector nut or the lapped parts inside the injector need to be relapped.
This is not an SD site but the injectors are the same.
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/617/07_1-137.pdf

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84 300D, 82 Volvo 244Gl Diesel

It looks like there is a fiting that goes in the head and the injecter threads into this fiting.The fiting,or cup,I was told it is called,looks like it has two notches in it and appears to be leaking between this cup and the head.

The thing with the 2 slots is the precombustion chamber retaining collar and the injector threads into the retaining collar itself (it looks that way in the pic). (I have heard of precombustion chambers being called Pre-cups before so maybe that is where the "Cup" came from.)
Here is a pdf with a pic, look at items #50 and #51.
http://www.pauldrayton.com/uploadfiles/merc/Service/W123/w123CD2/Program/Engine/617/07_1-230.pdf
You might want to do a search on precombustion chamber leaks as the question of bubbling fluid comming from this area crops up ounce in a while. So far it has always been something that has gotton inside the spaces from a previous leak of oil from the valve cover, fuel from bleeding the air out of the injector lines, fuel from previously leaking injector return lines or even water from a previous engine degreasing that has pooled inside passed the threads.
As long as what is comming out is not coolant or something that is currently leaking into that area don't worry about it.

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84 300D, 82 Volvo 244Gl Diesel