Being an idiot committed to doing things I probably should just leave alone, I decided to change the fuel filter on my Saab C900 (for those unfamiliar, it's a standard aluminum cannister with banjo fittings at either end). Old one came off without too much difficulty. New one came with new copper sealing washers. Bolts are different sizes, so it's easy to tell what goes where.
However, when the old one came off I saw that it had steel sealing washers with rubber embedded around the inner edge. These are looking pretty rough after 30 years, so I figured I'd just use the new copper. Fine, except they won't seal. Neither will the old rubber ones after being cleaned up. I can't crank down on the bolts any harder without fear of damaging the filter. Everything's as clean as I can make it. What the hell am I doing wrong here? I'd really like to get this thing back together today, so timely suggestions are most welcome.
Have any o rings around? A normal one should get you set enough for a while the you can get gas resistant ones to last long term
Might also try some spray on gasket sealer of the type used with copper head gaskets on the copper rings and/or try annealing them.
The rubber lined ones are common in hydraulics if you need another place to look for them.
Edit: Stefan beat me to it, and with the link ftw!
Well, for better or worse, it seems to be sealing at the moment. Figuring I had nothing to lose, I went full gorilla (well, as close as I can manage) on the bolts and that seems to have done it. I guess it just needed more squish. I'll keep an eye on it, but hopefully it's resolved.
The annealing tip is a good one. I'll keep that in mind for future problems.
I always used to pull those fittings, and re-install them, with the judicious use of a 3/8 impact wrench. Trying to tighten them enough with flat wrenches is not super easy, but a couple of light duty ugga-dugga's works nicely.
In reply to Streetwiseguy :
If there was room I would have happily impacted away, but access is fairly tight. The other problem was that the head of the larger bolt (the one that wouldn't seal, naturally) was so rusted that it was no longer whatever size it used to be, so I had to gently file the edges to make it 17mm so I could use a less agricultural tool to tighten it. An impact might have wrecked the "flats" I created.
