2 small threaded holes on each head
 

SOMEBODY PLEASE HELP ME???? I got a 400E and there are 2 small threaded holes on the front of each head that seem to have something threaded into them from the inside with nothing bolting to them outside and one of them is leaking oil when it runs. Does anyone know what they are and what I need to do to fix the leak correctly?I tried talking to a MB mechanic but he doesn't know what Im talking about!:mad::confused:

It sounds like you are describing the pins that hold in the timing chain guides. You can see them on the front of the heads and they have internal threads for when you need to remove them. You thread a slide hammer/removal tool into them to pull them out. Does that sound right?

most likely your inner upper rails have failed allowing the chain to rub against the rail pins. time to go visit the shop. these rails, unlike the 116-117 type, are curved and the chain actually rides against them.

Did anyone ever find a fix to this? Do I have to pull the valve covers off and replace the "inner upper rails"? I'm so confused. Any help would be awesome!