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PSA: Oil filler neck o-ring "failure"

21K views 16 replies 12 participants last post by  dash_martino 
#1 ·
Just a small PSA for those who may have some oil residue on the upper part of the engine block on the driver's side. I had some build-up but no real oil issues (no loss of pressure, no oil light, etc), just something that concerned me so I investigated further.

Turns out the oil filler neck has an o-ring at the base where it enters the block and it is known to wear out. The part is less than $3 from the dealership and has a slightly raised ridge in the center of the ring instead of just being flat.

Took me about 30 minutes to replace it (I always take my time) and I had to disconnect and remove the battery to get to all the bolts.

2 bolts hold the filler neck to the block then there is a bracket that keeps it stable with one bolt into the filler neck tube. I had to cut my old one to get it off the filler neck but the new one went on very easily.

You may not have an issue, but it's an easy fix and at $3, it's not a bad thing to replace to keep oil from misting out the filler neck base.

PART NO: 21191KA000
 

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#2 ·
I had a similar problem, except it was the o-ring under the oil cap that I lost.
A generic $6 "STi" oil cap off of fleaBay that looks MUCH nicer than the fugly yellow OEM one, and no more oily mist residue :tup:
 
#6 · (Edited)
Thanks Parker and Boots! bottom one was leaking, cap o-ring missing!
 
#7 ·
I too am having this problem. First I started smelling burning oil. Found location and cleaned the area ( had to fully clean the skid plate cause it already started to drip from it) noticed that the two bolts were a tad loose so I righted them and thought I fixed it. Month later same thing is happening again with oil dripping. Guess I need the o ring. Thanks
 
#8 · (Edited)
Great, thanks for this, I noticed a leak too and it seems to originate from the top of the engine on the driver side. I originally thought it could be the valve gasket cover or the intake AVCS solenoid but it did seem to come from the filler neck so I might try to replace this first. Here is a pic, do you guys agree this it might be the root cause ?

How common is that ?

 
#11 ·
Great, thanks for this, I noticed a leak too and it seems to originate from the top of the engine on the driver side. I originally thought it could be the valve gasket cover or the intake AVCS solenoid but it did seem to come from the filler neck so I might try to replace this first. Here is a pic, do you guys agree this it might be the root cause ?

How common is that ?

Image Link

That is 100% a dried up o ring on the fill tube causing that film, mine looked the same on my 06.
 
#10 ·
I was going to bring this up on here as well. When I pulled the engine in the STI, I noticed the oil imprint on the valve cover in quite a large spread that originated from the bottom of the oil fill tube, and it gives the appearance of a valve cover oil leak because of the way it travels down and to the rear lower corner of the valve cover.

It was obviously easy to remove and replace the tube with the engine out. The valve cover gasket was fine all the way around. A new O ring sealed it back up.

I also replaced my rear main seal while the engine was out and the flywheel removed. I dont think it was leaking but I did it anyway because I was already in there.
 
#12 · (Edited)
Yes, I replaced the filler tube today and could see a residue of oil post o-ring so I am 99.9% positive that this was the problem.

Thanks guys and OP, my gut feel was telling me it was coming from the filler but I just felt like it was pretty unlikely and was just bracing myself for a valve cover leak as it seems like that's what everyone talks about. The original post increased my confidence that it was the problem and made me remember that I had a spare :)

This was a much simpler fix
 
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