Hello all. Please be gentle as this is my first post. I have learned a lot from reading through the forums and am thankful for all the helpful advice that y'all have provided. Thanks!
OK, onto this bolt that has me mystified...
The bolt is located at the front top of engine block, centered between the oil dipstick and the valve cover, sitting low. There seems to be oil leaking from around the bolt head and today after tackling the oil cooler lines (modified to AN fittings) and updating the glow plug wiring (thanks for all the info on here!), I noticed air bubbling out around this bolt. Yikes.
Does anybody know what this bolt is?? I've been told it has something to to with injection timing? I have scoured the forums trying to find info and to no avail. The Haynes and Chilton manuals have no mention that I could find.

I have provided a photo for reference.

I am looking forward to hearing your replies.

Thanks much!

Attached Thumbnails

 

I can't figure out how to make the photo post.
Here is a link...
https://flic.kr/p/ooiYAQ

I have no idea what that bolt is for but I have noticed that there is bubbling around the one on my OM616 as well.

That is a cap for the oil pump drive bushing or 'thrust piece' as MB calls it. On a gas engine, the ignition distributor would go in that hole. The cap has an aluminum crush seal under it try tightening the cap. Should be a 22mm, maybe 24mm.

__________________
Cars:
1993 400E
1993 300TE Wagon
1985 300D Turbodiesel w/ 688,000 Miles On Original Eng/Trans
1979 300SD
1977 Euro 6.9
1967 230S IMA Universal Wagon
100 Or So Parts Cars

You Cannot Change your Future Without Disturbing Your Present

It Looks A Whole Lot More Like It Did Today Than It Did Yesterday?

Any idea where I may find more info on this element? I have had two people who know their way around these cars tell me not to mess with it and that it has something to do with tuning. Therefore I am a bit hesitant to just tighten it down without fully understanding what exactly that may do. I do want to get rid of all oil leaks on this vehicle, however, so I do want to address this.
Might you have any other information or ideas on where to find some? I've tried searching the terms you listed but have not found anything thus far.
Thanks mate!

Trust me, it has nothing to do with timing of the engine. I do not have any other info on it. I cannot find my 123 diesel maintenance cdrom to look it up. I have been working on Mercedes cars for 36 years. I usually replace the thrust piece when rebuilding an engine.

__________________
Cars:
1993 400E
1993 300TE Wagon
1985 300D Turbodiesel w/ 688,000 Miles On Original Eng/Trans
1979 300SD
1977 Euro 6.9
1967 230S IMA Universal Wagon
100 Or So Parts Cars

You Cannot Change your Future Without Disturbing Your Present

It Looks A Whole Lot More Like It Did Today Than It Did Yesterday?

@unaffiliated
Awesome, thanks for the advice. Man, you must be some sort of wizard, having worked on these cars for that long.

Well, I'm no wizard but I have learned a few things along the way. Thanks, CF.

__________________
Cars:
1993 400E
1993 300TE Wagon
1985 300D Turbodiesel w/ 688,000 Miles On Original Eng/Trans
1979 300SD
1977 Euro 6.9
1967 230S IMA Universal Wagon
100 Or So Parts Cars

You Cannot Change your Future Without Disturbing Your Present

It Looks A Whole Lot More Like It Did Today Than It Did Yesterday?

CF, I removed the cap bolt and found no seal. Replaced with a copper crush. I figured this would solve the problem but it seems that the leak is actually coming out from around the outer perimeter perimeter of the shaft that the cap bolt screws into.
Anybody have any ideas on what needs to be done to fix this leak??
Thanks much!!

Hopefully this will work. I found my repair manual cdrom. I will try to post the info on the thrust piece.

Attached Files

05-410.pdf (173.1 KB, 121 views)

__________________
Cars:
1993 400E
1993 300TE Wagon
1985 300D Turbodiesel w/ 688,000 Miles On Original Eng/Trans
1979 300SD
1977 Euro 6.9
1967 230S IMA Universal Wagon
100 Or So Parts Cars

You Cannot Change your Future Without Disturbing Your Present

It Looks A Whole Lot More Like It Did Today Than It Did Yesterday?

Let me know if you are able to view the document I attached.

__________________
Cars:
1993 400E
1993 300TE Wagon
1985 300D Turbodiesel w/ 688,000 Miles On Original Eng/Trans
1979 300SD
1977 Euro 6.9
1967 230S IMA Universal Wagon
100 Or So Parts Cars

You Cannot Change your Future Without Disturbing Your Present

It Looks A Whole Lot More Like It Did Today Than It Did Yesterday?

Yes, thank you. I will see if I can pull the thrust piece tomorrow. I have located the set screw on my engine which is a tight squeeze beneath the power steering pump. Should be able to get to it.
So it seems I can just pull the thrust piece (124 in diagram) up and out? I don't have to worry about any part of the helical gear shaft (126) doing crazy things? If that is the case and I can simply pull it, I am hoping just the o-ring needs to be replaced. How does one tell if the bushing (125) is worn to the point of replacement?
The pdf you provided paints it to be a simple job. However, I have no experience with these oil pumps....

Sorry for the late late response. I just wanted to say that is the cap for the thrust piece. That nut is just a cap. Be careful as I found two of these froze to the thrust piece when I was looking for a new one. There is also a 13mm? nut under the power steering pump bracket hard to explain that holds the thrust piece in think of it as a grub screw. Send me a message if you have any more questions sometimes I forget to look at my threads.

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