tkplay:

You don't have to mess with the timing chain or sprockets to change the cam seals. I replaced mine along with resealing the front head covers, because I couldn't tell whether the leak was coming from the cam seals or the head covers, where metal meets metal. The dealer's tech said that 119's are notorious for leaking at the front head covers.

If you are leaking in that area, even if you can get the cam seals out without removing and resealing the front covers (it looks like you can), if you're in that far and you already have the valve covers off, it makes sense to consider pulling the front covers and resealing them.

Once the front covers were off, the cam seals are easy to get out (no tool required). The cam seals fit over each exhaust cam. You will have to take off the rotors and caps to get to them. Looking at my picture that I took of the front cover, it looks like the seals actually came off with the front cover and can easily be pushed right out (I took the picture in 2001 before I had a digital camera).

You can probably get the new seals in without the tool, but I ordered the tool from the dealer and it wasn't very expensive if I recall. The most expensive part of the job was the MB factory orange sealant (part # 002 989 00 20 10). That cost me about $55 back in 2001. Some have argued that you can use a cheaper sealant, but just to be safe, I went with the factory stuff (8 years afterwards there were still no leaks).

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles