Umm oil cap mod?

[Stampy]

I don't know if this would qualify as a mod, but I figured you guys might find it interesting. I had caught some threads on other forums about people using the R8 vented oil cap. It is supposed to help relieve pressure in the valve cover. This in effect is supposed to help cut down on various leaks we all know about ( cam seal, valve cover). I guess there is a lot of confusion as to which R8 one is actually vented and it doesn't line up right anyway without cutting it, so I held off. In my research though I found that the 04 A6 2.7t had the vented cap stock. Actually Daft posted the part number in this THREAD, so thanks man. Vast sells it for $34 and figured I would see what the dealer wanted next time I was in. I ended picking it up on Friday for $20.47, and it looked way too big compared to my oem 4.2 one. I tried it in the parking lot and I was wrong, it actually fit fine. Just a much fatter lip kind of like the newer coolant cap that I have too. It hugs the engine cover, but still allows the venting.

Well tonight I decided to take the thing about and see what its all about. Pretty cool actually, and a lot more involved that what I thought it would be. I figured it would just have a few vent holes letting out air. I was wrong. Anyway, here are some pics that will help me explain this thing...

Here are the two side by side. Original 4.2 version on the left. You can see that the parts that actually see the motor are the same size. The cosmetic part is where the size changes.



Here is the new one opened up

I didn't expect to see the spring loaded valve in it.

This is what it looks like when you open it from the center passage on the underside.

This is it installed and showing that it fits like the old one did.



A reference for the difference in size.
OEM 4.2 cap

04 2.7t cap


I'm not sure if I like how it looks. I was never to keen on the R8 one since it would match nothing. I don't know if this thing will actually benefit me, but the money wasn't bad to try it. What do you guys think? Is there any reason I should put my stock one back on? Do you think it might actually help prevent leaks? Useless on the 4.2? I know if I had a 2.7t I would have it. I would assume Audi started using this in 04 for a reason.

The coolant reservoir cap I have on is a newer version too. I had to pick that one up cause my stock one literally fell apart one day. I really like how the newer one looks and it was like $9.

[itsjeo]

would that fit on a 3.0?
O_o

[scot_w]

Looking at the side by side pics the OEM 4.2 cap looks too small. I like how the 2.7T cap fills the space in the cover.

Keep us posted on the outcome. That would likely be the least expensive mod I could think of on my 4.2.