Vacuum Pump

A

al ross

New member
Jun 5, 1998
23
0
0
I purchased a vacuum pump from a wrecking yard today per Gene Fisher's
excellent instructions at the tech site. I am uncertain as to the
proper plumbing of the pump inlet and outlet connections as the engine
was out of the car. I understand having a tee connection between engine
and brake booster to the pump inlet. Wher does the pump out let
go??. Why not to open atmosphere?

Thanks again for the pictures and explanation on Patrick's site.

Alan Ross
78 Royal
Texas
 
Eugene--
This is exactly the kind of help that makes this site invaluable to
neophytes like me. Now I see how the system works!!! I know that I would
have messed up big-time without your help. Thank you!!!
Gary '77 Kingsley -- North Bend, Oregon Coast

> -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
>
> sorry about the confusion, see if this helps
>
> Plumbing
> To plumb in the pump, remove the vacuum line from the brake booster and
> connect to the filter.
> The other side of the filter goes to the pump exhaust. A new hose goes
> from the suction side of
> the pump to the brake booster.
>
> Installed this way, the engine sucks through the filter, through the
> pump, to the booster. The only
> time the pump comes on is when the vacuum is too low and then it helps
> the engine vacuum. If
> the engine stops, (goes up to ambient air pressure) the pump provides
> all of the vacuum. If the
> pump fails the engine provides all of the vacuum.
>
> Some owners plumb the pump Tee connected between the engine and the
> booster, a check valve
> is needed between the Tee and the engine. The pump will not be able to
> draw a vacuum in this
> configuration if the engine stops because the engine will bring the
> booster up to ambient air
> pressure. A check valve is necessary to block the engine. I do not
> recommend this
> configuration.
>
> Pump Orientation
> The pump must be mounted with the rubber mount bracket on the top.
> There are drain holes in
> the bottom of the pump that remove any moisture that might have
> collected inside the pump. If
> the pump is mounted upside down, it will have a short life.
>
>
> --
> Gene 76Palm Beach /Or/CA
>
> GMC Technical Information
> http://www.california.com/~eagle/
 
I have been reading with interest all of the posts here related to the
addition of a supplemental vacuum pump for the coach braking system. At
issue, as I understand it, is that in the event that the engine shuts-down,
we only have enough reserve vacuum for one (at best) application of the
brakes.

>From my days of performance "improvements" in my older Corvettes, which
always included a "lumpy" camshaft of obscene duration, I often didn't have
enough vacuum to supply my power brakes even with the engine running.
Needless to say, I missed having brakes at the end of the quarter mile.

The solution then, as now, can be exceedingly simple. Without relying on
an additional mechanical part (a supplemental vacuum pump that will also
shut down with the engine), you can add a vacuum reservoir that could give
you several attempts at stopping the coach. Over the road tractors use air
tanks for their brakes and racers frequently use vacuum tanks for their
brakes. Less things can go wrong when you keep it simple.

My intended solution inludes installation of a vacuum booster tank from
Jeggs or Summit Racing. Summit sells their base steel reservoir kit for
$33.95 (SUM-G1464) with fittings but no hose, and a matching guage for
$11.50 (SUM-G3125).

Am I missing something here? Or would this solution also achieve the
desired results? I am loathe to dig up a supplemental pump from a junkyard
and trust my brakes to it.


>To plumb in the pump, remove the vacuum line from the brake booster and
>connect to the filter.
>The other side of the filter goes to the pump exhaust. A new hose goes
>from the suction side of
>the pump to the brake booster.


- ----------------------------------'
Gary Thurlow
email to thurlow
St. Louis, MO
- ----------------------------------'
 
Gary, I don't know much about extra tanks, but the vacuum pump is a simple
addition and all it needs to do is to be a backup to the primary vacuum
system. When I installed mine and found it was running all the time I
suspected the pump was bad, but when I stopped up the hose, the pump stopped
at the right vacuum. However, that told me my booster was bad... thus it was
helpful in two ways. Replacing the booster with one from Bob Lamy gave me
great relief.

Regards
Al Chernoff

> I have been reading with interest all of the posts here related to the
> addition of a supplemental vacuum pump for the coach braking system. At
> issue, as I understand it, is that in the event that the engine shuts-down,
> we only have enough reserve vacuum for one (at best) application of the
> brakes.
>
> >From my days of performance "improvements" in my older Corvettes, which
> always included a "lumpy" camshaft of obscene duration, I often didn't have
> enough vacuum to supply my power brakes even with the engine running.
> Needless to say, I missed having brakes at the end of the quarter mile.
>
> The solution then, as now, can be exceedingly simple. Without relying on
> an additional mechanical part (a supplemental vacuum pump that will also
> shut down with the engine), you can add a vacuum reservoir that could give
> you several attempts at stopping the coach. Over the road tractors use air
> tanks for their brakes and racers frequently use vacuum tanks for their
> brakes. Less things can go wrong when you keep it simple.
>
> My intended solution inludes installation of a vacuum booster tank from
> Jeggs or Summit Racing. Summit sells their base steel reservoir kit for
> $33.95 (SUM-G1464) with fittings but no hose, and a matching guage for
> $11.50 (SUM-G3125).
>
> Am I missing something here? Or would this solution also achieve the
> desired results? I am loathe to dig up a supplemental pump from a junkyard
> and trust my brakes to it.
>
>
> >To plumb in the pump, remove the vacuum line from the brake booster and
> >connect to the filter.
> >The other side of the filter goes to the pump exhaust. A new hose goes
> >from the suction side of
> >the pump to the brake booster.
>
>
> ----------------------------------'
> Gary Thurlow
> email to thurlow
> St. Louis, MO
> ----------------------------------'
 
Yes, it is a clean looking pump and the price is right BUT a vacuum
switch is a must (maybe something is out there as a separate item???).
The filter is a simple off the shelf item in most auto stores for about
$7.00. My new pump with switch was $270 plus shipping.
Gary
'77 Kingsley
North Bend, Oregon Coast
 
Gary:

Although I have the GM part number (17070814 @ approximately $15.00) for the
carbon filter, NAPA says they can't cross it.

Do you have a brand/part number, with what you say below.

Paul Bartz

From: Gary Miller [mailto:grizzly]
Sent: Friday, November 27, 1998 11:54 PM
Subject: Re: GMC: Vacuum Pump

The filter is a simple off the shelf item in most auto stores for about
$7.00. My new pump with switch was $270 plus shipping.
 
Paul---
Vacuum Filter #675-5136, retail $10.60, Net $7.99. That is a NAPA part
number. I just checked with my supplier and he as some in stock.
BTW, in the process of checking out my vacuum pump installation I found
that I had a small leak in the original vacuum line to the
booster.....probably never would have found it until complete failure
had I not installed the pump.
Gary
'77 Kingsley
North Bend, Oregon (wet) Coast
 
The vacuum pump I used is a complete unit including the pump, vacuum
switch, and resilient mounting bracket --- everything you need except a
filter.
Pump: MP (Master Power) Brakes ---(704)664-8866 Part AC2723
$269.95 plus $20.30 shipping from NC to OR. Mounts easily on the
firewall "box" by the steering post under LH access panel.
Gary
'77 Kingsley
North Bend, Oregon (wet) Coast
 
You must log in or register to reply here.
Get your shine on at www.cruzingear.co
Applied GMC

Share this page

Share this page
Top Bottom
Back