There is a procedure for setting TDC and locking it without locking the cams. I'll give you a laugh on the 95 E300 the way you find TDC is as follows some kid must have come up with it. There is a jig you fit a spring loaded device that sits in the jig that falls into a TDC slot on the vibration damper when the dial indicator placed on the cam lobe hits zero whomever designed it did place the dial indicator on the inlet cam. The TDC procedure is not in the manual but there is a procedure for finding TDC.
It's probably a two hour plus job you have to remove the intake manifold and the cam cover and everything needed to remove it. The cam lobe I am sure it is not even at its apex at TDC so the dial indicator would be past zero. I do not remember if it calls for the dial indicator to be at zero or another reading. There is also another set of timing marks apart from the slot. There is a hole in the cam sprocket that you place a pin in to check the chain stretch or time the cams and there is no punch mark for TDC like is on the older diesels. The procedure is absolutely ridiculous as is the documentation for the 606.910.
The TDC would be locked by the jig with the spring loaded tool. I'll try and find the procedure again it is not in the FSM, if successful I'll post it even though it is ludicrous in my opinion. Perhaps an Mercedes engineer got upset with Mercedes mechanics and got even with all of them everywhere.

I'll chime in here, because I am in the middle of this job, and have lost even more hair off the back of my head.

There ARE two punch marks in the cams of the OM606.910 engine. If you remove the valve cover, and rotate engine by hand, and continue to turn until they line up, (drivers side cam punch mark @ 9, and passenger @ 3 - clockface references FYI) that is TDC. The lobes on the cams will be pointing UP as well when you get there.

It is very easy for the indicator on the flywheel to become FUBAR. This is a good way to cross-check it and see. It does require removing the valve cover though.

On my car there are no punch marks on the cams. There is a hole drilled in the cams. To get TDC you set the hole at 3 o'clock. There is no need to remove the cam cover the hole can easily be seen through the with the oil cap hole. You can see the hole long before TDC so there is not a problem using this method. There may be punch marks on your cams there are none on mine; the procedure says there are marks. If you want a post by Marshall Booth and Ned discussing this go to Okiebenz there are several post about this. That's the way I found out also the cam timing procedure show this too.

95 E300D 606.910 Setting Timing to 14.5 degrees BTDC
 

I got a conflicting comments on the post "Correction Injection Pump Timing". The procedure for R&R of the injection pump is incorrect. I reread the cam timing procedure to be positive I don't do it again. How do you find TDC on 606.910 (there are no pin punch marks on the cam sprocket) without removing the cam cover?

Define sprocket. Jeremy's 606.910 has alignment dots on the intermeshing sprockets, not the chain driven sprocket - http://www.peachparts.com/shopforum/diesel-discussion/300145-e300d-timing-chain-stretch.html

http://i323.photobucket.com/albums/n...iming_4708.jpg

[edit] Oh, [expletive]! This is Jeremy's 606.912. Sorry about that.

Sixto
MB-less