Best way to test Brake Booster? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Best way to test Brake Booster?

Engo LED Flush Mount Lights *PAIR* Flood or Spot 1,600 LumYukon Ultimate 35 axle kit for c/clip axles with Yukon ZipRockridge 4WD IS Taking Zone Offroad Suspension Lift Kits

Reply
Unread 07-20-2005, 12:22 PM   #1
longlimb
Registered User
 
Join Date: May 2005
Location: Tallahassee, FL
Posts: 341
Best way to test Brake Booster?

I think my brake booster is shot. When I press on the brake pedal and then start the engine, it doesn't go down any. The pedal is pretty far to the floor, if that gives anyone an idea as to whats wrong. I tried pumping the brake pedal and then turning the key, but nothing again.

Is there a way to test the vacuum line? can I just pull it off the booster and feel for air? I'm just learning how the vacuum system works so please excuse my ignorience.

Thanks all.

__________________
'79 CJ7 304 V8 T150, Dana 20, D30, AMC20 Rusty Beast! Stock except for the rust...
longlimb is offline   Reply With Quote Quick reply to this message
Unread 07-21-2005, 06:35 AM   #2
dawgates
Web Wheeler
1980 CJ7 
 
Join Date: Sep 2004
Location: Nevada
Posts: 1,276
Do you have a vaccum tester/gauge? Disconnect the booster from the intake/carb and hook up a tester/gauge. pump up the tester and see if the vacuum gauge stays up. If these a leak you see the gauge drop. I would replace the line as cheap insurance.

Another way if you don't have a gauge if to start you're Jeep with your foot on the brake pedal. Feel if the pedal try's to push your foot up. That won't tell you if you have a leak, but it will tell you if the booster is working or not.

If the M/C and booster has never been replace, remember it's at least 25 years old and the rubber inside does go bad after awhile. Maybe instead of testing this and that, you should just replace the whole set-up. Save a bunch of your time and money.
__________________
80' CJ7, 360 Howell Injected, 3" single exhaust, NP435 4spd, Dana 300 AA clocking ring, Currie twin stick, Tera-Low 4 -1 kit, Dana 44 front, cut 10" wider to 63", 4.10 gears, ARB, Yukon axles and Super H/D u-joints, Currie Dana 44 rear, cut wider to 60 1/2", 4.10 gears, ARB 35 spline, Currie 35 spline axle shafts, 2 1/2" x 11" Ford drum brakes, CJ-SOA conversion, Tom Woods F & R drive shafts, Warn 9500i winch, 6 point cage, Homemade F&R bumpers and tire carrier, 1" body, Pro Comp supension Kit, 12.5x35x15 BFG's, 15x10 OMF beadlocks, Body armor, OBA.
dawgates is offline   Reply With Quote Quick reply to this message
Unread 07-21-2005, 07:29 AM   #3
longlimb
Registered User
 
Join Date: May 2005
Location: Tallahassee, FL
Posts: 341
I was thinking the same thing. How much are the vaccum testers anyway? I can get a used wrangler booster for $65, but will have to mod. it to fit.
__________________
'79 CJ7 304 V8 T150, Dana 20, D30, AMC20 Rusty Beast! Stock except for the rust...
longlimb is offline   Reply With Quote Quick reply to this message
Unread 07-21-2005, 07:48 AM   #4
JFM626
Registered User
2004 TJ Wrangler 
 
Join Date: Feb 2005
Location: Tyee Capital of Canada
Posts: 1,789
The vaccum for a power booster usually comes directly of the intake manifold, you can of course check the line to be sure that it has not collapsed internally. At the end that connects to the booster there is a one way check valve, that sometimes fails. you should be able to blow air into it from the flat side(the side inside the booster), but not from the side that connects to the vaccum line.
JFM626 is offline   Reply With Quote Quick reply to this message
Unread 07-21-2005, 11:12 PM   #5
Vancopbs
Registered User
 
Join Date: Jan 2005
Location: South Gate, CA
Posts: 385
Quote:
When I press on the brake pedal and then start the engine, it doesn't go down any.
Bad booster and if its going to the floor possibly more is bad.
Vancopbs is offline   Reply With Quote Quick reply to this message
Unread 07-22-2005, 05:28 PM   #6
pyro9862
Registered User
 
Join Date: Mar 2004
Location: Long Island, NY
Posts: 1,532
A bad booster will make the pedal harder to push not easier. I'd be looking at the master.
pyro9862 is offline   Reply With Quote Quick reply to this message
Unread 07-23-2005, 01:43 PM   #7
Vancopbs
Registered User
 
Join Date: Jan 2005
Location: South Gate, CA
Posts: 385
Quote:
Originally Posted by pyro9862
A bad booster will make the pedal harder to push not easier. I'd be looking at the master.
You're right, what the hell would I know.
Vancopbs is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 07:34 AM   #8
longlimb
Registered User
 
Join Date: May 2005
Location: Tallahassee, FL
Posts: 341
Id does seem hard, but I have nothing to reference. I bought the jeep this way and it's the 1st CJ I've owned with power brakes.
__________________
'79 CJ7 304 V8 T150, Dana 20, D30, AMC20 Rusty Beast! Stock except for the rust...
longlimb is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 08:01 AM   #9
pyro9862
Registered User
 
Join Date: Mar 2004
Location: Long Island, NY
Posts: 1,532
Throwing parts right and left at somthing trying to fix it gets expensive unless you have money and you just want to be safe and replace all the 25 year old parts.

To test the booster you need a vacuum pump like this. You can the cheap plastic version with no case at autozone for about $25, I think craftsman has one to or do what I did and find a used one on eBay for the same price with a case and loads of hoses and adapters. If you go the used route just make sure the seals are good and it holds vacuum. I don't find myself using this very often so if you can borrow one for a few days you're better off saving the money. On the plus side it does double as a vacuum gauge.

Anyway as has already been said put that on the line to your booster and pump it up. The vacuum should stay constant. If it doesn't remove the line completly from the booster plug one end and put the pump on the other and pump it. If you loose vacuum the line is bad if you don't you're loosing vacuum from the booster.
pyro9862 is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 12:04 PM   #10
Vancopbs
Registered User
 
Join Date: Jan 2005
Location: South Gate, CA
Posts: 385
You guys are making this too hard.

1. Start the car let it run 30 seconds turn it off. Wait 30 seconds.

Remove the check valve (the plastic piece the hose connects to in the booster). Did vacuum release? Yes, go to 2. No bad booster.

2. Start the car let it run 30 seconds turn it off. Step on the brake pedal and hold it.

A good booster will stay down, a bad booster will either immediately come back up or come back up after a few seconds.
Vancopbs is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 12:06 PM   #11
longlimb
Registered User
 
Join Date: May 2005
Location: Tallahassee, FL
Posts: 341
Thanks pyro- I'm definitely don't want to be replacing parts just for the fun of it. I'll see if I can find someone with a vacuum pump.
__________________
'79 CJ7 304 V8 T150, Dana 20, D30, AMC20 Rusty Beast! Stock except for the rust...
longlimb is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 12:08 PM   #12
Vancopbs
Registered User
 
Join Date: Jan 2005
Location: South Gate, CA
Posts: 385
Quote:
Originally Posted by alindbloom
Thanks pyro- I'm definitely don't want to be replacing parts just for the fun of it. I'll see if I can find someone with a vacuum pump.
Don't do it! Just call me when you're by the Jeep I'll walk you through it.
__________________
Van
Vanco Power Brake Supply
9738 Atlantic Ave
South Gate, Ca 90280
800-256-6295
323-563-1588
Vancopbs is offline   Reply With Quote Quick reply to this message
Unread 07-25-2005, 12:14 PM   #13
longlimb
Registered User
 
Join Date: May 2005
Location: Tallahassee, FL
Posts: 341
Hey vancopbs-

I'll give your idea a try. No money is always better. But if the boosters bad on your step 3, wouldn't the lack of vacuum keep the pedal down? Or am I thinking of it backwards? I'm thinking of it backwards, the vacuum would pull the brake pedal down for assistance. duh.
__________________
'79 CJ7 304 V8 T150, Dana 20, D30, AMC20 Rusty Beast! Stock except for the rust...
longlimb is offline   Reply With Quote Quick reply to this message
Unread 07-26-2005, 11:16 AM   #14
rhk109
Registered User
 
Join Date: May 2004
Posts: 11
Quote:
Originally Posted by Vancopbs

2. Start the car let it run 30 seconds turn it off. Step on the brake pedal and hold it.

A good booster will stay down, a bad booster will either immediately come back up or come back up after a few seconds.
How long do you hold the pedal down in step 2? Do you mean that the pedal will stay down if the booster is good?
rhk109 is offline   Reply With Quote Quick reply to this message
Unread 07-26-2005, 11:18 AM   #15
Vancopbs
Registered User
 
Join Date: Jan 2005
Location: South Gate, CA
Posts: 385
About 10 seconds. If the booster is good you'll apply the brake and hold it. It'll stay down if it's good. If it comes back that means it's loosing vacuum. Just hold down normally.
__________________
Van
Vanco Power Brake Supply
9738 Atlantic Ave
South Gate, Ca 90280
800-256-6295
323-563-1588
Vancopbs is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.