Date:         Fri, 8 Mar 2002 18:15:43 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: For WBX Owners with Suspected Head Leaks(vs. sniff)
Comments: To: paulmayfield@earthlink.net
Content-Type: text/plain; charset="US-ASCII"

In a message dated 3/8/02 2:20:54 PM, paulmayfield@EARTHLINK.NET writes:

<< Is sniffing with a smog probe as good/better test?
If so, you could save quite a few bucks.
 >>
In general, the sniff testers are low grade Mass Spectrometers or Ion
Mobility Analyzers with limited dynamic range due to real time sampling of
gas through a differential pumping system. In other words, a sample of gas is
drawn into the analyzer and about 1% of the gas sample is analyzed in real
time.

The chemical sensor approach is different in that it integrates the signal by
capturing all the gas coming out of the coolant. So you can let it collect
gas for minutes, tens of minutes or hours. Small leaks are best detected with
the chemical sensor approach, while large leaks will be readily detected by
the sniffer approach.

I posted the info because:

1. I thought it was cheap compared to diagnostics charges.

2. The analysis was in one's own hands. With age I have come to distrust the
minimally informed wielding black boxes with inadequate understanding or
calibration procedures.

3. In either case, I was trying to counsel analysis as opposed to
speculation, informed judgment and teardown.

Frank Grunthaner