Arkady, my understanding is it's the carbon conductor that wears out.  But either way, you are sort of right, wearable parts should be replaceable.  In this case, I guess the part is replaceable -- the whole AFM that is ;-) .  DMc

---- Arkady Mirvis <arkadymirvis@GMAIL.COM> wrote:
> Tom,
> Yours is one describing the AFM eventual failure in simple terms. Thanks. I
> never looked inside the part and would think that the manufacturer had an
> obligation to have the part ( wiper ) which wears down to be a replaceable
> part. I understand that no two variable resistors can be absolutely
> identical, but I was involved in sophisticated production and dealt with
> resistors with no more than 5% difference. The design was allowing perfect
> adjustments. Hope that some heads on the list will eventually find the best
> and economical solution.
> Ark
>
> ----- Original Message -----
> From: "Tom Hargrave" <thargrav@hiwaay.net>
> To: "'Arkady Mirvis'" <arkadymirvis@GMAIL.COM>; <vanagon@GERRY.VANAGON.COM>
> Sent: Friday, March 05, 2010 8:45 AM
> Subject: RE: AIR FLOW METER
>
>
> > Ark,
> >
> > Problem is it's a variable resistor that continuously changes value as you
> > are going down the road based on airflow through the meter. And the value
> > changes by a wiper sweeping back and forth across a carbon track.
> > Eventually
> > the wiper wears through the carbon track & when this happens the unit gets
> > intermittent and then eventually fails. And since this is a wear item they
> > will all eventually fail.
> >
> > Some mechanics have figured out how to fix some of bad ones by relocating
> > the wiper so that it sweeps through a new track but once you wear a track
> > across the carbon the values are not exactly where they were from the
> > factory.
> >
> > I've often wondered if the working parts from inside another airflow
> > meter,
> > maybe something more readily available, could be retrofit into a failed
> > Vanagon airflow meter. Bosh manufactured millions for a lot of different
> > cars and some of the parts have to be common.
> >
> >
> > Thanks,
> > Tom Hargrave
> > 256-656-1924
> >
> > Our Web Sites:
> > www.kegkits.com
> > www.stir-plate.com
> > www.andyshotsauce.com
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
> > Arkady Mirvis
> > Sent: Friday, March 05, 2010 1:56 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: AIR FLOW METER
> >
> > Expensive part! Are failures common? What causes the failure? What are the
> > symptoms and consequences of AFM failure? Please name the sources. Ark
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 9.0.733 / Virus Database: 271.1.1/2718 - Release Date: 03/04/10
> > 13:34:00
> >