My 1984 w123 300D euro model recently had a catastrophic failure of the crankshaft pulley. It turns out that there were two broken bolts on the pulley and a large crack in the pulley which gave away and tore apart. Luckily it didn't hit the radiator.

So, we began pulling parts and got everything cleaned up and ready for installation. I searched all sites for tips and was almost ready to use the plastic cup "tool", when my better judgment told me there must be a way to recreate the factory tool. And, there is. I used a kit made by Private Brand Tools PBT 70960 which removes seals and installs them. It worked so well I thought I would post it for those trying to stop front oil leaks, and would rather not stick thin plastic drinking cups into the opening to the timing chain of the engine. The kit has multiple mandrels and plates that can be assembled to create a tool that allows the spacer ring and the seal to be installed simultaneously, thus preventing seal lip curl and loss of the spring. I tried to attach some pics showing the tool and how it is assembled, but I can't seem to get this site to accept my pics (Sorry). I used the old crank bolt for installation of the seal and replaced it with a new one when I installed the harmonic balancer.

I also noticed in the Mercedes Shop Manual that there are two types of oil pans, and the seal which the classic center sent me is not the one the shop manual says to use on mine (says I need half shoulder). Classic center said they only use the one version now (full shoulder). Has anyone else noticed this difference between what the manual says and what Mercedes uses? I hope this assists.

As an aside, I noticed the vibration dampening pulley which has the rubber layer embedded in it, is showing breakdown of the rubber. Mercedes has 2 in Germany and they want over 1K for it ($800 with discount). Has anyone found an import version?

Assembly sequence for the seal installer from the PBT kit is...

Press new spacer ring into new seal front to back.
1. Old Crankshaft Bolt
2. Bushing No. G-M18
3. Adapter Plate
4. Mandrel No. 7
5. Install Sleeve K
6. Mandrel No. 4

Insert new seal with new spacer ring into the tool and seat in opening. Use the old crankshaft bolt to slowly pull the seal and spacer ring onto Crankshaft snout. I used a little Mercedes bearing grease for the shaft and it slid on easily.

A picture is attached to this thread...

Replacing Front Crankshaft Seal with Special Tool