I’m doing an engine transplant on my 1989 300SEL and I’ve got the donor engine out of the wrecked car and on the garage floor. I was looking it over and notice some, not a lot but some, oil and grime around the rear crankshaft seal. I figured it would be a great time to do the rear main seal, just to be safe.
In checking my All Data, it said to pry out the old seal with a screwdriver and then use a special tool to set the new seal. Does anybody know if I must use this special tool, or is there a technique I can use to get the new seal in place? I did some extensive research in the archives and the best reference I could come up with was this sentence from a previous post:

“Yes you can put in a new seal without special tool just remove rear crankshaft seal cover punch oil seal out install new seal,seal the cover with sealer.”

I’m not sure what this means. Can anybody help me out?

Thanks!

It's pretty easy.
There is a big aluminum "collar" or seal cover that the seal presses into.
This "collar" (I forget the real name) can be unbolted and removed, then the seal can easily be pressed out and a new one installed. Sliding the new seal with the collar attached back over the end of the crankshaft can be delicate, but just oil it up well and take your time.
1. Unbolt the collar, including the two bolts that come up from the bottom.
2. gently work the collar loose, try not to damage the oil pan gasket along the bottom edge. Or you can pull the pan and replace the gasket if you have the engine out).
3. Clean up the mating surface of the collar, replace the oil seal.
4. Carefully clean the engine mounting surface, especially along the oil pan gasket.
5. Apply plenty of gasket sealer, oil the seal surface and work the seal/collar into place.
6 Install and tighten the two bottom bolts first (10NM).
then tighten the horizontal bolts (10NM).

Keep it clean and don't tear the seal lip.

DG

Thanks for the information DG. This is exactly what I needed.
I haven’t had it apart yet, and I suppose I’ll be able to tell when I do, but do I apply the gasket sealer around the perimeter of the “Collar”? Also, can you recommend a gasket sealer? Sorry for trying to detail what may seem the obvious, but I don’t want to have to dig into it again, after she's together, because I made a poor assumption.
Thanks for the help!

Sorry for late reply; been real busy.
Yes, apply the sealer all around the areas of the "collar" that contact the engine; basically the front and bottom of the collar. Use special care to clean in the corners along the bottom where the oil pan joins the block and the pan gasket may be frayed. Use iso alcohol to clean, or any good gasket cleaner. I used Permatex blue gasket sealer - MB may make a special mega$ sealer that is better than Permatex, but I highly doubt it.
It's all very straightforward and obvious when you get in there. The only touchy thing is slipping the seal lip over the crank. Be sure the crank edge is very smooth so the seal does not get cut; lightly sand the corner of the crank flange if it's not really smooth. (then clean it of course).

DG

Thanks DG, for the detailed and easy to follow instructions. I know I can get it done now. I really appreciate the help.