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Discussion Starter #1
I think I've replaced the o-ring on the distributor shaft maybe three times on my S4 Spider, so while I pulled the distributor recently for other work, I lightly applied some Permatex Ultra Grey sealant around that o-ring. I also applied a light coating to the immediate area on the outside of the seal gland, the machined flat on the block. Surely, with this I should be able to finally conquer this pesky leak.

If you try this, just be sure no globs of sealant get down into the hole for the dizzy drive. You do NOT want silicone circulating in your oil and plugging an oil passage! And be certain the distributor seats completely down into the recess, with the drive tang engaged, to compress that o-ring.
 

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The O-ring should be set in place in the recess of the timing cover before the distributor is inserted. It should not be put on the distributor first. I'm sure you knew that already.
 

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Discussion Starter #3
The O-ring should be set in place in the recess of the timing cover before the distributor is inserted. It should not be put on the distributor first. I'm sure you knew that already.
Yup... but you know Ed, there doesn't seem to be much compression on that ring anyway. Maybe it's my rubber guy imagination.
 

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when the ring sits in the front cover groove, it is not sitting proud, true, but as the distributor shaft gets pushed through it (you'll notice it is a tight fit) the ring gets expanded a bit and should seal.
dizzy seals for the front cover, when I last looked were ID 26,57mm ID with 3.53 mm CS/cross-section

better still, perhaps use two like here:
https://www.alfabb.com/bb/forums/8345074-post11.html

according to the german forum a BMW/Victor Reinz O-ring (for Bosch dizzy) apparently fits the shaft itself.
BMW put the O-ring on the shaft itself.
https://www.rmeuropean.com/Products/12118530508-MFG17.aspx
 

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Discussion Starter #5
Dom, I do NOT have a second o-ring in that groove on the shaft itself. I never recall seeing a seal there, and I'm the original owner of this S4. It would make perfect sense to have one there, so am I actually missing this seal? That would explain this pesky little leak, alright.

Anyone else know of this second o-ring on this Bosch Motronic distributor?
 

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It would make perfect sense to have one there, so am I actually missing this seal?
No, there was never a 2nd O ring on the shaft of our cars.

I was just pointing out that it might be an idea to try out...:)
 

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Discussion Starter #7
ok--- that's good to have confirmed. But I agree that's a perfectly machined groove for an o-ring, if I ever saw one. Next time I'm in there, I might size up that gland and get a standard 2- size ring to fit it. Thanks Dom!

Don't you just love the Alfa BB? :grin2:
 

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ok--- that's good to have confirmed. But I agree that's a perfectly machined groove for an o-ring, if I ever saw one. Next time I'm in there, I might size up that gland and get a standard 2- size ring to fit it. Thanks Dom!

Don't you just love the Alfa BB? :grin2:
How can you not? Soo many great contributors with great experience always available to assist.
 
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