| Re: [GMCnet] My First Vapor Lock (Vacuum Booster Pumps) [message #175426] |
Tue, 03 July 2012 12:55  |
Dave Mumert
Messages: 272
Registered: February 2004
Location: Olds, AB, Canada
Karma:
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Senior Member |
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Hi All
I was ignoring this thread, we don't get vapor lock often up here in the
Great White North.
When it comes to making a fail-safe vacuum source for the brake booster I
think you are both wrong.
One of the fundamental principles of fail-safe design is the elimination of
common sources of failure.
The original vacuum source has only three parts, the hose fitting on the
manifold, the hose and the vacuum port on the booster. All these have
proven to be very reliable, as a primary system they should not be modified
in any way.
Adding a vacuum pump in series with the original vacuum hose adds a number
of failure points that are common to both the primary system and the
secondary system which actually reduces reliability. I have to agree with
JB here, don't mess with the original vacuum feed. It has been reported
here that a failed vacuum booster pump not only caused a loss of vacuum to
the booster but also pumped air into the manifold killing the engine.
The little vacuum pump GM used was intended as a vacuum booster and was
plumbed to provide that function. I assume we are attempting to get a
redundant source of vacuum so plumbing the pump as GM did is probably not
the best way.
Adding a vacuum tank by teeing into the original vacuum hose also adds
multiple new failure points.
In my opinion the only way to get a redundant vacuum feed that is (almost)
as reliable as the factory system is to use a booster with dual vacuum
ports.
If you like a vacuum tank hook it to the extra vacuum port and connect it to
its own vacuum port on the manifold.
If you like the idea of a pump then connect it to the extra vacuum port and
let it exhaust to the atmosphere.
I personally like a vacuum pump. The engine will provide less vacuum than
the pump, so in theory you should get better brakes with the pump running.
I would also connect the pump to the brake light switch, through a relay of
course.
These are just my opinions, feel free to ignore them or critique them as you
see fit.
Dave Mumert
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