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Re: [GMCnet] Tranny modulator vac line [message #133190] Sun, 03 July 2011 12:20
Gary Casey is currently offline  Gary Casey   United States
Messages: 448
Registered: September 2009
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Senior Member
Matt is right, but if the modulator fills with fuel it will still work, although
with maybe slower response. I would go ahead and use a rubber line. Not worth
worrying about.
Gary Casey

JShot wrote on Sat, 02 July 2011 19:53
> Is there any reason the vacuum line from the transmission modulator can't be
>replaced with standard vac hose. Is there a reason it is a steel line?
>
> John

John,

I asked this question years ago at one of the OE design groups and was told that
the line was steel because A - that would be difficult to mis-connect or
mis-route during assembly, B - it did not require multiple tie points to keep it
out of danger, C - the steel line provided a restriction feature to slow the
response of the modulator, D - the steel was a good enough heat sink to cause
the fuel vapors to collect and run back into the intake instead of down to the
modulator where they could collect. Once the fuel fills the line to the
restriction, the modulator stops responding at all.

Matt
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