Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

88 K5ers Simple question ... please

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by backlash, May 16, 2001.

  1. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    When you stomp on your brakes, do you hear the woosh of air at the firewall? Sounds like a bad shock absorber ...pedal moves but no pressure for 2-3 in.

    When I remove the check valve from the booster it stops and I have extremely hard braking ... you guessed it, manual.

    When I reinstall the check valve I hear this woosh of air and a squeak behind the firewall ... is it possible that I have a bad , brand new booster?

    I know this is the second post but need to get some inputs ...

    Thanks
     
  2. ChevyCaGal

    ChevyCaGal 3/4 ton status

    Joined:
    Dec 16, 2000
    Posts:
    8,158
    Likes Received:
    0
    Location:
    Sacramento, CA USA
    I don't have an 88, mines an 86 and it does that sometimes....I had it checked out (I don't do brakes, something I refuse to mess with they are too important for me to mess up) and they said there's nothing wrong with them. That whoosh had me concerned. I guess it's nothing because it's been 2 years and no problems....I think maybe it's just a sound they make? I hope so! That'd suck if I had bad brakes- DOH!

    "Suck Fumes Ford Boy"
    "I love my country, I fear my government"
    <A target="_blank" HREF=http://www.chevycagal.homestead.com/steph.html>http://www.chevycagal.homestead.com/steph.html</A>
     
  3. Greek

    Greek Registered Member

    Joined:
    Jan 29, 2001
    Posts:
    9
    Likes Received:
    0
    Location:
    Long Island, New York
    i have an 88 k5 and it makes the same noise. I asked my mech. and he said theres nothing wrong with it. So i guess its supose to make that noise.
     
  4. shane

    shane 1/2 ton status

    Joined:
    May 6, 2001
    Posts:
    162
    Likes Received:
    0
    Location:
    Prince George, BC, Canada
    my 91 doesn't make noise when I brake unless I jump on the brakes with both feet and then it's the tires making the noise, not the booster. [​IMG]

    Just keepin it Canadian[​IMG]
     
  5. Pookster

    Pookster 1/2 ton status

    Joined:
    Nov 21, 2000
    Posts:
    3,195
    Likes Received:
    0
    Location:
    NYC, NY, USA
    mine does that as well. Scary acutally, because if I press on the brakes quicky, they will engage without the woosh, but if I do it slowly, it seems like the woosh is taking away some of the power. *shrug*
     
  6. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    How much travel in the pedal before you have pressure when pressing slowly?

    Any one get a squeak when taking their foot off the pedal? Any idea what this may be? Air in the lines or a dry bushing?
     
  7. 85k5blzr

    85k5blzr 1/2 ton status

    Joined:
    Jan 10, 2001
    Posts:
    103
    Likes Received:
    0
    Location:
    Houston, Texas
    My 85 does the same thing. Brake Check said that it was the master cylinder going out, but then i asked another mechanic and he said that it is common and more than have of the master cylinders in the world make that sound.

    K5 just upgraded to rig status! [​IMG]
     
  8. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    Thanks Steph,

    How much free travel do you have before the brakes apply? Can you lockem up?

    After 3 M/C's in 2 years The pedal's finally off the floor and stops pretty good. But I can't for the life of me ... lock them up. I still think the squeak behind the firewall is air in the lines.

    PS What happened to Hokey Pokey? Get some doo doo?
     
  9. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    Thanks for the response El Grecco ... still not so sure!

    Welcome ... fill out your profile ... tell us who ya are and where you're from and stuff!

    Thanks again

    Back
     
  10. DBLAZER

    DBLAZER 1/2 ton status

    Joined:
    Apr 2, 2000
    Posts:
    1,716
    Likes Received:
    0
    Location:
    Haslet, Tx
    When I had my stock brake booster mine made that sound, now that I have my double diapram booster, NO MORE SWOOSHING!!!!!!!!!!!!!!

    [​IMG]
    http://autotronixcaraudio.com
     
  11. ChevyCaGal

    ChevyCaGal 3/4 ton status

    Joined:
    Dec 16, 2000
    Posts:
    8,158
    Likes Received:
    0
    Location:
    Sacramento, CA USA
    Not much...I don't have to mash them down much. I do somewhat, but that's cuz it's a heavy truck and when you have to brake when you are going 65mph it tends to take a big mash.......

    I took it off...too much crap in the sig that's why.... lol

    "Suck Fumes Ford Boy"
    "I love my country, I fear my government"
    <A target="_blank" HREF=http://www.chevycagal.homestead.com/steph.html>http://www.chevycagal.homestead.com/steph.html</A>
     
  12. CaptCrunch

    CaptCrunch 1/2 ton status

    Joined:
    Feb 2, 2001
    Posts:
    3,596
    Likes Received:
    1
    Location:
    Minnesota
    Usually is the Brake booster starting to leak internally.... you could also check that the check valve is workin properly... If it is fine I'd just live with the swoosh until the booster goes out unless you have too much cash burning a hole in your pocket... then I'll give you an address to send it [​IMG] and I'll turn up your radio... no more swoosh LOL [​IMG]

    [​IMG]
    1987 Chevy K5 Blazer- 350 TBI
     
  13. Espen88k5

    Espen88k5 1/2 ton status

    Joined:
    Feb 19, 2000
    Posts:
    981
    Likes Received:
    0
    Location:
    Norway
    I have a 88. It's a diesel but I remember reading in the users-manual that came with the truck that the brake-pedal will do som strange things, and they are suposed to, like continue traveling if you hold it down as hard as you can, while stopped. And posibly something about braking hard if you stomp on it, braking soft if you ease the pedal the same distance. Maybe thats your woooshing right there.

    Of litle help I know, but when I get back to work I'l scan the part of the manual I am thinking about and post it.

    [​IMG] <A target="_blank" HREF=http://www.espen88k5.coloradok5.com>http://www.espen88k5.coloradok5.com</A>
     
  14. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    Did the new booster have any affect on your braking?

    If so was it dramatic?
     
  15. jimmyjack

    jimmyjack 1/2 ton status

    Joined:
    May 11, 2000
    Posts:
    2,290
    Likes Received:
    0
    Location:
    Tucson Az
    I noticed mine was a constant sound of rushing air. The brake worked normally but I swapped it out anyway. Depending on the warranty, I'd re replace it. Its not a difficult job.

    "My blazer may be slow, but it goes faster at higher speeds"

    Jim
     
  16. Nrose07

    Nrose07 1/2 ton status

    Joined:
    Mar 29, 2000
    Posts:
    267
    Likes Received:
    0
    Location:
    Salem ,Or
    OK, mine does it too (88'K-5). But one question, is it a one time swoosh as you depress the brake pedal OR a continuious hiss as long as the brake pedal is down. Mine is the hiss and I was told that as long as it only does it while depressed (opposed to all the time) it ok. It's annoying, and my brakes stop me, but don't have a real firm feeling. Thanks for the help.

    Displacement, cubes, and did you say you drive a riceburner???
     
  17. newyorkin

    newyorkin 1 ton status

    Joined:
    May 8, 2001
    Posts:
    16,555
    Likes Received:
    157
    Location:
    Los Estados Unitos
    I was just thinking about this the other day!

    '88 K5, identical problem(?). This one with the whoosh is an auto. I had another '88 before this one, with a 465 (relevance-different brake pedal) that DIDN'T do this at all. I also tuned and tightened the crap out of the rear brakes every couple months in that truck (auto adjusters never seem to work for me).
    I think the pedal squeak is the actual GM auto-tranny-vehicle brake pedals. Every automatic GM I've owned has had that squeak, and I think I tracked it down to the actual mounting point a couple years ago.
    I'm not sure, but I think the whoosh and delay are loose rear brakes. The rears apply first, and if they're out of adjustment, they take longer, equalling longer pedal travel (the whoosh), less braking power until the fronts pickup the load. How's the travel on your parking brake? Mine goes all the way to the floor.
    I also suspect one caliper to be siezed or line to be collapsed on my truck, which might cause the same thing. I'm yanking it all apart saturday morning...


    Does that sound right?

    Ratch
    **Hmmm. Land or Mall? Land or Mall? Let's see. Lotsa SUV's around here... Let's build a mall.**
     
  18. Triaged

    Triaged 1/2 ton status

    Joined:
    Feb 21, 2001
    Posts:
    3,808
    Likes Received:
    0
    Location:
    CA (LA/OC area)
    The wooshing sound is normal (Maby the prob is that your engine and stereo arn't loud enough). That much play sounds excessive to me. The play could be 2 things. The pushrod that goes from the booster to the maser could need adjusting or the rear brakes may need adjusting.

    '71 Blazer CST with alot of rust
     
  19. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    I was always under the impression that the "whoosh" I heard in many different vehicles with vacuum-assist brakes is the vacuum-assist doing it's job... evacuating the air from a chamber in the booster, thereby increasing the line pressure to the brakes.
    It's definitely not fluid flow noise; the braking system doesn't move enough fluid for that.
    Now we need to hear from someone with Hydroboost brakes!!

    BTW, my auto '87 has the whoosh when I stomp on the pedal, but not when I'm easy on it.

    [​IMG] Semper Maintenance!
     
  20. backlash

    backlash 1/2 ton status

    Joined:
    Oct 21, 2000
    Posts:
    519
    Likes Received:
    0
    Location:
    Northern, VA.
    Mine only does this while depressing the brakes ... it's like a no man's land ... just a hiss before the brakes apply. It is not continuous.
     

Share This Page