Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1987 - 1996 F150 & Larger F-Series Trucks
Sign in using an external account
Register Forgot Password?


1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Welcome to Ford-Trucks Forums!
Welcome to Ford-Trucks.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Ford-Trucks Forums community today!





 
Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 03-12-2014, 09:08 AM
reno138 reno138 is offline
New User
 
Join Date: Feb 2014
Posts: 14
reno138 is starting off with a positive reputation.
Wooshing sound when you step on brakes

1987 ford f-150 4x4 351 motor.
I have a soft pedal when I step on the brakes. I have ajusted the rear shoes. So that they have a slight drag. But still have a soft pedal. When I first step on the pedal I hear a quick Whoosh. Does this mean the vaccum booster is bad. Or how would I check it?
Reply With Quote
  #2  
Old 03-12-2014, 09:14 AM
Conanski's Avatar
Conanski Conanski is online now
Post Fiend
 
Join Date: Jun 2006
Location: Ottawa, Ontario
Posts: 20,421
Conanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud ofConanski has much to be proud of
Yeah I'd put money on it being the brake booster, they fail in several different ways but all related to the vacuum diaphram leaking in some way or another.
__________________
Paul (Conan) O'Brien

1990 5.0HO AOD XLT X-Cab F150 3.55LS, 1994 3.0L 5-sp x-cab Ranger 3.45, 2004 3.0L 5-sp X-cab Ranger Edge 4.10, 2004 2.5L 5-spd Subaru Legacy
1996 Kawasaki ZX11D, 2004 Honda 599, 2008 Kawasaki KLR650
Reply With Quote
  #3  
Old 03-12-2014, 09:34 AM
luthoro's Avatar
luthoro luthoro is offline
Senior User
 
Join Date: Jul 2011
Location: O'fallon, Missouri
Posts: 177
luthoro is starting off with a positive reputation.
Conanski- my understanding was that usually when a booster fails the result is a very stiff pedal that takes a ton of effort to push, not a spongy/soft one? Is that not the case?

OP- does it hold a steady amount of pressure when you're on the brake, or does the pedal sink? Also check for vacuum leaks, and make sure the booster is getting plenty of vacuum.

I'd start by checking the entire system for leaks, and if none are found it could be the master cylinder is bad. Of course if you replace the MC thats a good time to replace the booster too. That said, the fact that you're hearing an air "whoosh" when you apply brake could support the booster theory.

I'm sure someone with more knowledge will chime in, I could be wrong.
Reply With Quote
  #4  
Old 03-12-2014, 11:29 AM
dixie460's Avatar
dixie460 dixie460 is offline
Posting Guru
 
Join Date: Nov 2011
Location: SW Florida
Posts: 1,854
dixie460 has a good reputation on FTE.dixie460 has a good reputation on FTE.
A quick whoosh when you step on the pedal ain't nothing to fret over. Now if it makes a continuous noise while you hold it down, then yes your brake booster is failing. It won't be hard to push the pedal til the diaphragm blows out, in my experience.

BUT: that shouldn't give you a soft pedal. When you're stopped and put pressure on the pedal, does it slowly sink toward the floorboards or stay put?

I assume you already looked around for leaks, but have you checked the master cylinder itself? Usually what kills a booster is the master cylinder blows a seal (on the pushrod end, the end of it facing the driver) and brake fluid leaks into the booster. The fluid eats the seals in there, and then you get a leaky booster.

Might wanna loosen the MC up and take a look... but usually you can see the crap running down the front of it. Either way, if you replace the booster then get a new MC or at least inspect your current one so that it don't trash your new booster.
__________________
96 F-150 SCSB - 351W - Rebuilt E4OD - Manual 1356 T-Case Swap - 3.55 Gears - 31x10.50x15 Falken WildPeaks - York 210 OBA - 130A Alternator - MileMarker Supreme Lockouts - Badlands 12K Winch - Dual Thrush Glasspacks - LED Headlight Conversion
Reply With Quote
  #5  
Old 03-12-2014, 05:05 PM
RIKIL's Avatar
RIKIL RIKIL is offline
FTE Chapter Leader
 
Join Date: Sep 2008
Posts: 1,930
RIKIL has a great reputation on FTE.RIKIL has a great reputation on FTE.RIKIL has a great reputation on FTE.RIKIL has a great reputation on FTE.RIKIL has a great reputation on FTE.RIKIL has a great reputation on FTE.
I have a new brake booster and no vacuum leaks so my system is working great and each time I press the brakes I hear what I would also call a 'whoosh' sound. I think this is normal operation of a brake booster, at least it seems to be for the one I have. So I would think just hearing this sound doesn't mean you have something wrong.

Have you checked the front brakes to see how they are?
__________________
RIKIL - Colorado Chapter Leader
--------------
Red, 1992 F150, 351W, E4OD, Vortech V-2 Si trim blower, Snow Performance water/meth injection system, custom cam, Edelbrock Performer intake, Twisted Wedge 205cc heads, shorty full-length headers, MASS Air (converted), tuning with QuarterhorseRT, 4x4, short bed, 33" tires
Reply With Quote
  #6  
Old 03-12-2014, 08:52 PM
88n94 88n94 is offline
Posting Guru
 
Join Date: Jan 2004
Location: South Dakota
Posts: 1,228
88n94 is gaining momentum as a positive member of FTE.
You say you have a soft pedal when you step on the brakes, that can have a lot of interpretations. I assume the pedal goes almost to the floor before the brakes work? What happens when you pump the brake pedal several times? Does the red brake light in the dash ever come on when you hit the brake pedal? Does the red brake light come on when the key is in the start position, so you know it is working? A good way to check that is don't press the clutch down or with an automatic transmission put in reverse or drive and turn the key to start.
__________________
88 F=150 4X4 4.9l 5speed. 94 F-150 4X4 5.8l automatic overdrive.
Reply With Quote
  #7  
Old 03-12-2014, 09:06 PM
88_F0RD 88_F0RD is offline
Junior User
 
Join Date: Feb 2014
Posts: 71
88_F0RD is starting off with a positive reputation.
vacuum booster test

Quote:
Originally Posted by reno138 View Post
1987 ford f-150 4x4 351 motor.
I have a soft pedal when I step on the brakes. I have ajusted the rear shoes. So that they have a slight drag. But still have a soft pedal. When I first step on the pedal I hear a quick Whoosh. Does this mean the vaccum booster is bad. Or how would I check it?
Power brake booster (vacuum operated)

(boring wish I had a scanner)

Begin the power booster check by depressing the brake pedal several times with the engine off to deplete any vacuum remaining in the booster.

Now, depress the pedal and start the engine. If the pedal goes down slightly operation is normal. Release the brake pedal and let the engine run for a couple of minutes.

Turn off the engine and depress the brake pedal several times slowly. If the pedal goes down farther the first time but gradually rises after the second or third depression, the booster is airtight.

Start the engine and depress the brake pedal, then stop the engine with the pedal still depressed. If there is no change in the reserve distance (the distance between the pedal and the floor) after holding the pedal for about 30-seconds, the booster is airtight.

If the pedal is "hard" when the engine is running (the booster isn't operating properly)

IF a defective booster is not diagnosed from those checks, inspect the check valve.

To do this, disconnect the vacuum hose where it connects to the metal pipe or the intake manifold (don't disconnect it at the booster). Apply pressure and suction to the end of the hose, making sure air only flows away from the booster. If it flows in both directions or if there is no airflow at all, replace the check valve. On some vehicles the check valve is located inside the hose, requiring replacement of the hose.

A restricted exhaust system could also be the cause of low vacuum.

Note: some engines are fitted with vacuum pumps which help generate vacuum to power the brake booster and other accessories. A defective pump will most often make a loud rapping sound that rises and falls with engine speed.

You can also test the operation of the operation of the vacuum pump as outlined in the engine vacuum check in the next paragraph.

(Connect a vacuum gauge to the booster hose) Place the shifter in park if the transmission is an automatic) block the wheels and start the engine. Allow the engine to reach normal operating temperature, then look at the gauge - there should be at least 15 in-Hg indicated at idle. If not diagnose and repair the cause of low vacuum before condemning the power booster.

Note : Engines with high performance camshafts will have a lower and somewhat erratic reading at idle.

here is just a listing of possible causes for the brake pedal "spongy" when depressed:
1.Air in hydraulic system.
2. brake shoes not centered in drum
3. brake drums machined to thin or excessively worn
4. cracked brake drum
5. brake shoes distorted
6. caliper or caliper mount flexing
7. master cylinder or power booster loose
8. brake fluid overheated (beginning to boil)
9. brake fluid contaminated
10. deteriorated brake hoses (ballooning under pressure)
11. soft of swollen caliper seals
12. defective residual check valve
13. broken brake pedal pivot bushing or bracket

and solutions (in order)
1 bleed the system inspect system for a leak
2 inspect drum brakes mount shoes correctly
3 inspect drums replace if diameter exceeds maximum allowable diameter
4 carefully inspect drums replace if necessary
5 replace brake shoes
6 inspect calipers and mounts for loose fasteners, cracks and other signs of fatigue. replace as necessary
7 tighten fasteners
8 bleed the system (temporary fix) replace the brake fluid (proper fix)
9 replace brake fluid
10 inspect hoses replace as necessary (it's a good idea to replace all of them if one hose shows signs of deterioration)
11 replace seals (if seals are swollen due to contamination flush entire system and replace all rubber components)
12 replace valve, bleed system
13 replace pivot bushing or repair bracket
Reply With Quote
  #8  
Old 03-13-2014, 07:59 AM
blue924.9's Avatar
blue924.9 blue924.9 is offline
Posting Guru
 
Join Date: Feb 2013
Posts: 1,327
blue924.9 is starting off with a positive reputation.
are you used to driving a different vehicle? i have found that these trucks have a softer brake pedal than most other cars , even if they are in good working order. mine also makes a very short woosh noise when i step on the brake pedal, and mine stops just fine, just my 2 cents
__________________
No matter how hard the "gangstas" try..... My tractor will always have bigger rims than their lowriders
Reply With Quote
  #9  
Old 03-13-2014, 08:12 AM
subford's Avatar
subford subford is offline
Post Fiend
 
Join Date: Aug 2005
Location: Easton,Ks
Posts: 17,041
subford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud ofsubford has much to be proud of
Quote:
Originally Posted by Conanski View Post
Yeah I'd put money on it being the brake booster, they fail in several different ways but all related to the vacuum diaphram leaking in some way or another.
X2, that is the way they fail.
Or at least the bad ones I have had did.
__________________
95 F150 302 4R70W EB EX-CAB
94 F53 460 E4OD COACHMEN SANTARA RV
83 F150 Flare Side 351W AOD
77 F250 351M-2V NP 435/4 Speed 4X4
subford@gmail.com
Bill K, Kansas Chapter
Reply With Quote
Old 03-13-2014, 08:12 AM
 
 
 
Reply

Go Back   Ford Truck Enthusiasts Forums > Older, Classic & Antique Trucks > 1987 - 1996 F150 & Larger F-Series Trucks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
1999 F150 ANOTHER SOFT PEDAL PROBLEM, HELP!! CAPTUPER 1997 - 2003 F150 14 03-27-2013 09:53 PM
1990 F 350 soft brakes nmichael 1987 - 1996 F150 & Larger F-Series Trucks 9 06-01-2011 11:25 PM
2000 F250 Brake Pedal Goes Soft on Bumps lasmacgod Super Duty & Heavy Duty 18 08-19-2010 04:40 PM
Trucks with adjustable brake pedal. Soft Brakes???? dinikin 1997 - 2003 F150 1 12-15-2009 06:23 PM
Soft brake pedal? berry1234 2007 - 2014 Expedition & Navigator 17 08-11-2008 04:42 PM



All times are GMT -5. The time now is 09:58 PM.


Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup