91quattro

I replaced my fuel filter today and thought I would share my experiences. 2005 A8L with 104K miles. As described in other posts on this forum, I found the filter just in front of the right rear wheel, beneath a plastic underbody tray held in place by 6 plastic 10mm nuts and 3 plastic clips. Once the tray was removed, the filter was right there. I jacked the rear wheel off the ground and was able to access everything.

As others have reported, I was unable to unthread the triple square nut holding the filter in place - so had to cut it with a hand-held hacksaw blade. I was hoping to avoid cutting the bolt, since this car spent almost all of its life in the dry climates of Arizona and Nevada. But, not too bad, really, maybe 10 minutes of cutting and I was done. I used a couple of zip ties to secure the new one. The filter was original - picture below shows it was manufactured late April 2004, and the car came off the assembly line in early June 2004, so virtually no time lag there. Made in Austria was a bit of a surprise. I used a new Mann WK730/1 filter which I got from FCP. The old one was a KL 79 (Mahle), I believe the WK730/1 is a direct replacement.

Anyway the job was straightforward and simple, the lines came off pretty easily and snapped right onto the new filter. Then test for leaks (none) and reinstalled the underbody cover. Note, the plastic nuts are "integrated" with the washers and the underbody tray. If you end up with nuts and washers as separate pieces, then you didn't unscrew the nuts right - as you unthread the plastic nuts, try to pull the tray off to keep them integrated to their washers, which are on the inside of the underbody tray. I messed up all 6 of mine, not knowing how these nuts and washers worked, but was able to "reassemble" everything pretty close to original.

On the test drive I immediately noticed a smoother idle, and when the AC is shut off, you hardly even know the engine is running. So there must have been some dirt or contamination in the old filter that restricted fuel flow at low RPM. Acceleration from a stop seems a little quicker (but that might be my wishful imagination - kind of like how your car seems to run just a little bit better right after it is washed...)

After 13 years, replacing the fuel filter was a worthwhile investment of $10 and an hour or so of time.



Original filter - Mahle KL 79

Dr Roy

What did you cut exactly? The plastic near the bolt?

91quattro

I cut the bolt itself. There is a gap in the plastic mount, just enough room to fit a saw blade and cut the bolt just below the bolt head. Doing that left the mount intact and once I had the new filter in there, I used zip ties to strap it to the mount so it wouldn't move.

I should also have mentioned that my car has had a slightly rough idle for some time now. New plugs helped, but not 100%. This new filter cleaned it up.

Panelhead

My car spent the first nine years on Long Island. Sprayed the nut with PB Nut Buster several times. Let it soak for a couple hours. Backed right off.
This may not always work, but it made a job I expected to be tough very easy.

Brozee

Cut it open and post a picture of it. I replace the filter every 2 years or so. Doesn't take long, and it is a cheap filter.

91quattro

Here you go. It is pretty filthy. The light colored particles are hacksaw shavings. The filter element is basically black throughout. Wish I had done it sooner!



Closeup...the light colored particles are hacksaw shavings.



After 13 years and 104,000 miles.

aTOMic

I'm about to do mine. Can't wait to see what's in there! I'm going to use my oxyacetylene torch so there won't be shavings.

Hold my beer and watch this!!

Panelhead

A can opener will clip right on the seam. Takes 5 seconds to remove the top. Then the bottom.
I like the idea of changing again. Did mine 3 years and 20,000 miles ago.

91quattro

Can opener is a great idea. My wife probably wouldn't agree so I'll be sure to have my own by the time the next filter change rolls around.

2004A8L

I replaced mine twice in 30k+ miles