I just finished replacing the spark plugs, cables, distributor cap/Suppressor Housing, and rotor. I also purchased separately the distributor cap O-Ring seal (because it was shown next to the cap on the parts catalog) but could not see where it has to go. When I took off the old cap there was no O-Ring anywhere to be seen, and no, I did not just drop to the ground without my knowledge. On the other hand I checked job No. 15-3010 of the MB W124 shop service manual that describes the replacement of the distributor cap and rotor, and there is no O-Ring shown explicitly as a separate part of the assembly diagram either.

The new O-Ring is brown in color, very similar to the cap's color, but on the car the closest I saw to it is a black/dark flattened seal mounted on a groove on what the catalog calls the "suppressor cover" (called "sealing washer" (3) in the MB manual) which is a round yellowish plate that turns freely and is mounted behind the rotor. I could not remove it because the rotor follower/adapter (the metal part where the rotor is mounted) needs to be pulled with a special removal tool which I did not have on hand. This "seal", although about the same diameter of the new O-ring, is very stiff, not flexible like rubber, it feels more almost like plastic. I gently tried to pry it off the groove for inspection with a small screwdriver, but it would not even move or stretch, so I left it alone for now to give me time to research the matter before proceeding any further.

Can someone confirm that this is the correct location of the distributor O-ring seal? Maybe that stiff seal that I see now are the remnants of the o-ring that have stiffened over the years because of the hot/cold engine cycles. Since the old seal will most probably be destroyed or at least damaged during removal, I just wanted to make sure I'm on the right spot.

Thanks.

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300E 1986 - 117KMi
Sikkens Metallic Azurite Blue
Member #120 of MB Club VE
Caracas, Venezuela