1984 300D Injector leaking
 

I've driven this car 500 miles now trying to get use to any noise it is or will make after seating for 12 yrs. Initially I thought it was the valve cover gasket that was leaking, I sprayed the area with white gas so it will dry everything and revealed where the leak is coming from. After all the miles I put on, the leak is coming around the injector area. The injector seem to have some insert where it threaded into.

Can someone educate me how these injectors are installed on the head? If I remove the injector, the insert I am referring to, will that come out also having the right tool to unscrew it?

If I were you, I would replace my injector return lines and see if the leak doesn't stop. Chances of success are outstanding. Chances of the leak originating as you describe are almost nil.

X 2 ... most likely culprit is the return lines ...

X3 on the return lines

In answer to the question about special tools - yes - searching for "pre-chamber removal tool" with or with out "home made" will bring up loads of information for you on this site (and others)

In answer to removing the injector - no the pre-chamber will stay in place - well it bloody well should do!

If you remove an injector you should replace the little heat shield that fits under it.

In the diagram #50 is the Ring that you are asking about that indeed needs a special Tool to remove.

That Ring does double duty. It is the Retaining Ring For the Prechamber by way of external threads and also the Injector threads into the Center of it.

In the pic I drew some orange lines. Those lines represent a space between the Injector and the Prechamber. What happens id when you have a leak the fluid seeps between the threads of the Prechamber Ring/Injector and fills that space.

When you run the Engine with it like that it looks like there is a Prechamber leak because you see some bubbles.
While it is possible for a Prechamber to leak in normal use Carbon Build up in the space around the Neck and there is empty area between the Prechamber and Head where the Prechamber gets wider; that also fills with Carbon an seals everthing.
I don't know for sure but I believe the bubbling is caused by the shock wave of the Fuel being injected and ignited.

When the actual Injector does leak it of most often between the upper and lower 1/2 of the Injector. Sometimes removing the Injector and re-torquing it solves the issue. More often you need to take the Injector apart and lap the precision surfaces inside of the Injector.

After that the little Fuel Hose Return Nipples are swedged/crimped into the upper Injector Body. Sometimes they become loose. No way to fix it but to replace the upper body.
Some people cut the nipple off and weld over the bad nipple area and move that Injector to last Cylinder where there is no need for 2 return Hose Nipples.

It also happens that sometimes the Fuel Injection Line that screws onto the Injector develops a crack or Pin hole.

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Thank you everyone for the quick response the email with valueable information. the reason I use the white gas (coleman fluid) it does a good job in Neutralizing any petrolium base product, which leaves a dry and clean area. I sprayed the entire area with it, the fitting and the return line area are dry and all the wetness seen on the photo is coming from the (pre-chamber) fitting.

It seems to be a problem according to "mercedes source" tech, so now all I have to do is get a set of those "home made" tools and fix this. I read a lot of post with members making these special tools and selling them. those of you still making them and selling them, I am in the market for a set. I have the slide hammer to extract the pre-chamber.

Again thank you very much for everyone's input and Miss Doris thanking you as well.