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Discussion Starter · #1 ·
I've done everything I can think of here.... bought a nice repro from Classic Alfa, bent the sheet metal tabs down, used a spacer. Clocked it to max the clamping force. Always get weeping. While it may not look right, do any later model Alfa oil caps swap on and perhaps provide a more positive closure?
 

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My suggestion, get yourself a good used original cap. I had one of these repros and they are terrible. The tabs are weak and the material is sub-par. The 40-50 year old caps are better.
 
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Discussion Starter · #3 ·
I do have one ill need to dig out of a box. Will try this.
 

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there is a rubber gasket under the cover -- it gets hard and brittle -- I dont know if they are available anywhere, I just cut one out of an inner tube -- two actually-- and rubber cement them together. Note that there is also a thin metal spacer there as part of the assembly.....
 

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Excessive crankcase pressure will push oil out of there. If you've got a '73 I believe you've got the oil vapor separator can? If so those tend to rust internally and plug up.
Yea, that was my thought. These oil filler caps are not designed to be 100% oil tight - they don't need to be - the inside of the engine should be at a lower pressure than atmosphere. You could try disconnecting the hose running from the cam cover to the oil vapor separator - maybe wrap a rag around the open end to collect any weeping - and see if that stops the filler cap from leaking. Or see if you can freely blow into the oil vapor separator's inlet.
 
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Discussion Starter · #8 ·
I replaced the oil vapor separator with one of the stainless units that were sold a while back. I’ll give those ideas a try as well.
 

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What's on the outlet of the vapour separator? A filter? Could that be very restrictive? Could the pipe to the separator be restrictive?
 

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From your photo...I see that one tab is distorted more than the other....this will cause the seal to not seat flush all around...hence slight leakage will result. I would do as GTA Alfa suggests....get out your original oil cap and try that. The chinese stuff never gets the alloy or thickness or geometry or even the heat treatment right in general....they just try to make it look the same....but often times the just fail.
 

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Yeah, its really got to do with the quality (or lack of) of the repro. I had them side by side and you can tell just by looking at them. The original weighs more, the tabs are thicker and stronger. The gauge used on the repro is thinner. Just a poor replica.
 

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I replaced the oil vapor separator with one of the stainless units that were sold a while back. I’ll give those ideas a try as well.
If your OVS is the SS variety.. ( I have no experience with them) .. I think they used a wadded up SS wool media.. I think ....It is a good design but probably needs tending to frequently . Rust is not a problem but dirty oil; will hypothetically restrict it ... Try flushing it out with an oil solvent and a final detergent like DAWN by plugging the two little nipples and the down draft tube then filling it with solvent and shake and bake. While you are at it ... connect a catch can or plastic bottle vented to catch the vapors from the cam cover.. It should stop the oil lid from weeping. Rust is the killer on the OEM units. Hope that helps!
 

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Discussion Starter · #14 ·
Thank will give that a shot. I only have a few thousand miles on that stainless unit but will check it nonetheless. Without a doubt the old cap fit a lot nicer I’m gonna start there put some hard miles on it and see if I get any weeping.
 

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the difference of 0.035mm thickness is EXTREMELY material in this application. I would advise you discard the replacement and use the OEM one.
 

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If the surface of your cam cover is scratched etc the it will weep a tiny bit as the rubber gasket can’t deform enough to squish down into the valley of the scratch to seal it.
 
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