Hi,
After I got my car back from the bodyshop I was snooping around in the
front left fender area, and came across a round plastic hollow ball with
a vacuum line attached to it. The ball isn't bolted to anything, just
sits on one of the fender supports, and you can move it around easily. I
never hear it rattling around. I didn't even know it existed before I
snooped around, so I don't know if the bodyshop knocked it off it's
support, or if it was always just sitting there. Anyway, what is this
thing ? Not the charcoal cannister, right ? And where does the vac hose
go ? Maybe part of the cruise control ? Thanks


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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

I think it is a vac canister. It holds vacuum (sorta).

Dale

 

Not quite sure, but it sounds like you're talking about the vacuum reservoir.

Jason

 

Sounds like a vaccuum resevoir to me, too. It's used to store vaccuum for power brakes, climate controls, and the like in cars that don't make much vac at idle.
My car has one in the same spot you describe.

------------------
88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

Correct, vacuum reservior, but not for the power brakes.

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

is this part required by the car? I want to put my air filter down in that area.


WS6 Trans Am.

View My Ride @ thirdgen.org

 

Try disconnecting the vacuum lines and drive arround a while. If the car stalls or acts crazy... then YES it is required!

I am pretty sure it is involved with the charcol canister, which is an emmissions thing. If you don't have the e-check, then you may not need it.


------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

The round ball in the left front fender area is the vacuum tank, which is part of your cruise control.
jms

 

No, you can trace the lines back to thier source and plug them.
SSC

 

Whatever it is, it's supposed to be bolted onto something, right ? Mine is just lying in there on top of a fender girder.

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88 GTA 5.7 TPI Charcoal Grey Bone Stock except for loose muffler which makes it a bit louder than normal.

 

Not exactly sure but I thought it was used to deploy the Air Bag in the event of a front collision hard enough to break it open

 

Nope that has nothing todo with the airbag at all. The airbag system is its own enity , totally seperate from the rest of the car.

All it is a vaccum resovior thats all.

Kat

[This message has been edited by Kat (edited September 13, 2001).]

 

It's the vacumme reservoir and I would leave it in if I were you. It is supposed to be bolted under the charcoal canister with two bolts.

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Riccioli Performance Motorworks

--RPM Racing--

Getting there.....383 with Super Ram, Bosch 24# SVO's, MSD, Edelbrock 58 mm TB, 700R4 tranny, Eibach springs, Koni 12 way adjustable shocks and struts, and more!! Now let's pray it runs when it's all back together!!!!

 

Airbag? I have the ball thingy on my 83, and im pretty sure I dont have an airbag (:P). Im also pretty sure that thing is avacuum cansiter for cruise control. It has a vacuum line going to the cruise control diaphragm if im not mistaken.

------------------
1983 Firebird
TH700R4 Auto
Small Block 400
LG4 ECM, Intake, Carb, Distributor, etc.
Soon to be non-computer.
Clarion Head Unit 45X4
2 Pioneer 400W 12" Subs
Third Gen Performance
"A four cylinder is half an engine."
"Ponies can run, but birds can fly..."

 

That particular vacuum reservoir is for the cruise control system. My car didn't have it, I put it in as part of my cruise install. Cars without cruise likely won't have it.


------------------
"Beware he who would deny you access to information, for in his heart, he dreams himself your master"

'84 Black Camaro Sport Coupe ZZ4 350 M6 -- '84 Olds Cutlass Supreme 231 A3
'91 Medium Blue Metallic Z28 400 A4 -- '99 Navy Blue Metallic Firehawk #120 346 M6

 

Just to add my .02¢ my 87 IROC
does not have cruise control and
I do have the vac. res. in the left
fender ????

------------------
TPIS airfoil,relocated MAT,AFPR,TB h2o bypass
March Underdrive Pulleys
otherwise stock 5.0TPI
700r4, 10 bolt 3.23 g92 axle, 4 wh. disc brks.

 

The vacuum reservoir is actually for all the little vacuum doors that control the ventilation airflow behind the dash. It should have 2 vacuum lines going to it: one from manifold vacuum which might be t-ed off of the same line that feeds teh cruise in cars with cruise, and the other will go to the A/C control head.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

Finally a correct answer, man I was getting worried about the knowledge of people here.



------------------
86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

Well some what. The actual vac resivor that controls the vent funtion for the climate controll is located just to the left of the wiper/washer motor, it has two lines, one from the manifold and the other from the canister to the controlls located in the car. This is square shaped box that controlls vent funtion. The ball shaped on which was on my camaro dealed with the cruise controll and was located on the inner fender near the cruise controll modual by the washer fluid resivor. My firebird does not have this ball instead the cruise controll was self contained "no resivor" running off of the vaccume line mess, basicly direct manifold vaccume. What is being described in that particular location is what ive seen/removed on many trucks and that is an overflow tank for the charcol canister. Basicly it acts as a leaching field if there is ecsessive fuel dumped into the canister.
Whatever it is in your case, your car will run fine without it and it isnt hurting anything be being there. GM put it there for a reason, whatevcer that was it does serve a funtion. OS leave it on and play safe or take it off and see if anything bad happens. If anything bad happens spread the word.
SSC

 

funny, mine was removed, and now i have problems with my vent only comming out of the defroster, thats the only thing it has affected. ac still works normal.

 

Funny indeed...

The defroster is part of the ventilation system, and is controlled by your A/C control head as described above.

The reason your air only comes out the defroster vents is because when all the little doors relax to their "rest" position, i.e. no vacuum, that's where the air comes out. By removing that ball (and not hooking up the vacuum source to the A/C control head some other way) you killed your HVAC system, since now there's no vacuum to work the air doors.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

That's not entirely true. If you have the the one by the wiper motor, you probally wont have the ball under the battery.



------------------
86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

I only read one correct reply so far.... It is for the a/c. It stores vacuum for the blend dooors and such when the engine loses vacuum.

------------------
1983 T-top Trans Am. All stock (for now) LG4/auto/3.73 posi. 70,000 original miles. SLOWLY going through a Knight Rider conversion. (it will be done one of these years)

 

I've seen a bunch of newer thirdgens lately that don't have the cylindrical reservoir above the brake booster, and I was wondering where the vent controls got their reserve. Now I know. I guess I'll never know exactly what made GM change it though.

HOWEVER:

Early cars that have the reservoir by the brake booster, and do not have cruise, do NOT have the spherical one under the battery. I know, I had to add it to provide sufficient vacuum storage for the cruise control.

What I noticed before installing it though, is at prolonged WOT the vents would relax to the defrost position. Now that it has been installed, that no longer happens, as the vacuum line for bothe reservoirs tees together right near the brake booster.

My conclusion is that the cylindrical vacuum reservoir above the brake booster wasn't big enough, and the addition of the spherical one has added enough reserve capacity to keep that from happening... that, and I don't spend as much time at WOT as I used to due to the replacement of the 2.8 with the 5.7.

Don't say that you've only read one right answer just because that's what the thing does in YOUR car. I've also spent a lot of time defending the fact that my car didn't have a VSS originally as well.

 

If you will re-read MY answer above, you will see where I said the ball is PART of the cruise control.

Which it IS!

It also happens to help store vacuum for the hvac controls.

If you have access to f-body shop manuals, look up the cruise control systems drawings.

The drawings include THAT ball as part of the cruise control system. It does serve another purpose but the "t" fitting for the hvac controls is (on my '88 GTA-at least) near the rear of the intake plenum, on the passenger side.

jms

 

Yes the cruise uses the ball for vaccumm but not all cars had cruise and ALL cars have HVAC so that's what the ball is for. It is just a easy place to pick up vaccumm for the cruise.


------------------
86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

I agree about the HVAC comment but if you'll notice, the original post was made by a GTA owner.

I don't think any GTAs came without cruise.
jms

 

Should this ball hold vacuum with a hand pump?

------------------
1989 IROC-Z 5.7L
NOS 5151 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System

 

Wow, 27 replies for a simple question.
Vacuum canister for cruise control. It can be moved about anywhere by lengthening the hoses. I put a cone airfilter in it's place when I built a home made cold air induction.

------------------
Rob P
89RSconvtZZ4TPI Edelbrock Intake
SLP Dual Cold Air Intake 1 5/8" Headers Semi-Siamesed Runners, IROC
suspension, alum shaft. Numerous mods.
92Z28convt5spd (stock)
71Impala convt 402BB
BETTER DRIVING THRU SUPERIOR HORSEPOWER!

 

Sorry Rob, it's really for the HVAC system. That's why this post is so long.


------------------
86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

These quotes are coming from my 1988 Helms FACTORY service manual for Firebirds which is almost identical with my FACTORY 1987 Camaro service manual (very worn and tattered. Could be a missing page or two). Almost. Very similar to my Chiltons 3rd gen Camaro service manual.

Remember, the discussion concerns a 1988 GTA. The hvac controls were somewhat different for other versions of the third gen f-body, especially taking into account years of manufacture, options on a particular car, and running changes through a model year.

Please excuse any typos and your version of this manual may have a slightly different page number as they sometimes were revised.

'88 Helms- page 1B-3 (air conditioning), SYSTEM COMPONENTS CONTROL, Vacuum Tank---"During heavy acceleration, the vacuum supply from the carburetor drops. (MY NOTE: This IS an '88 Manual-it does say carbuerator and we all know carbs were gone after 1987.) A check valve in the vacuum tank maintains vacuum so that, under load conditions, vacuum will be available for continuous use."

This is word for word what the '87 Camaro Helms says in my book, page 1B-3.

Page 1B-23 of the '88 Firebird book shows a diagram of the A/C control vacuum diagram. You can see the vacuum tank, the line, the 'tee', the engine vacuum source and the routing to the controls.

The '87 Camaro book does not have this drawing. However, on page 1B-30 there is a view of the vacuum tank mounted above the brake booster, as mentioned in one of the above posts. This is not on the '88 GTAs. The '88 GTAs have the plastic ball we are discussing.

As has been said before, the plastic ball (vacuum tank) is PART of the hvac system.

NOW, in the '88 Firebird Helms manual:
CRUISE CONTROL 9B-1, General Description, starting at the second paragraph--"The main parts of the cruise control system are the mode control switches, controller (module), servo unit, speed sensor, vacuum supply, electrical and vacuum release switches, and electrical harness."

Page 9B-4, VACUUM SUPPLY---"The vacuum to operate the Cruise Control servo can come from: manifold vacuum connected straight to the servo, from manifold vacuum through a VACUUM STORAGE TANK (my emphasis), or straight from a vacuum pump."

The factory diagnosis goes through several checks when there is a problem, including repeatedly saying to check for pinched or leaking vacuum lines.

The next few pages (9B-6 through 9B-10) have diagrams (drawings) showing the various cruise set-ups on the different engine versions.

EVERY ONE (of those engine vacuum drawings) SHOWS VACUUM LINES FROM THE ENGINE TO THE CRUISE CONTROL SERVO WITH A 'T' TO THE VACCUM TANK.

These drawings are similar to those in the other manuals.

My point, all along, has been that on the '88 GTA mentioned at the start of this thread, the plastic ball, located under the battery area (driver's side fender area on an '88 Firebird GTA) is PART of the cruise control system...

PART OF the cruise control system.

As it is PART OF the hvac system.

Technically speaking, the engine is part of the hvac system, and the engine is part of the cruise system.

Does that make the engine ONLY PART OF the hvac system?

GM (as do most other manufacturers) tries to get multiple uses out of parts, wherever they can.
jms




[This message has been edited by jms (edited September 16, 2001).]