I should probably wait for Dennis' response, but....... I think that the
crack allows oxygen into the exhaust stream, the O2 sensor adds fuel to
correct, and viola, you're rich out the pipe.

Jake

On 2/17/07, jon <jon@kenneke.com> wrote:
>
> Cool. It's nice it was a "simple" problem. I always like to read the
> solution to folks' problems, so I can learn.
>
> Ok, experts: why does a leak cause increased HCs? I'd imagine it has to do
> with decreased backpressure.
>
> I'll file this one away for future reference!
>
> Jon
>
> On Sat, 17 Feb 2007, Mike Frost wrote:
>
> > I found a nice big crack in the exhaust just outside cylinder two. It
> was
> > about 1.5 inches long and wrapped almost halfway around the pipe.
> >
> > Our emissions test stations close at 1:00PM on Saturday so I had to come
> up
> > with a quick and dirty fix to see if I could pass. I picked up a
> "muffler
> > bandage" (cringe!) for about $3.00. As per the instructions, I cleaned
> the
> > affected area and wrapped it with the bandage, adding the included wire
> that
> > holds the thing in place while it is curing. The drive to the test
> station
> > was just about the right length to meet the instructions for the
> bandage.
> >
> > I pulled into the emissions place at 12:55PM and ignored the glare from
> the
> > guy at the gate. Lo and behold, my HC was down to 125 (was 225) and CO
> was
> > down to 0.09% (was 1.5%). So the leak was definitely the root cause. I
> > managed to avoid opening the AFM for now.
> >
> > The crossover pipe will be replaced as soon as I can afford it, I plan
> to
> > just swap out the whole system in front of the cat converter since that
> and
> > the muffler have been recently replaced. Man, those pipes are expensive!
> > And, the parts jobber told me they can't get it anymore, he sent me to
> the
> > VW dealer. Original parts for the exhaust may be drying up, although I
> see
> > that Van Cafe has what I need.
> >
> > Thanks once again to everyone who pitched in to help me on this one.
> >
> >
> > Mike Frost
> > 86 Vanagon GL "WasserLeaker" aka "Completely Exhausting"
> >
>

--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com