1997 - 2000 GM OBS Truck Loud Hissing Air Sound ~ Brake Vacuum Booster Replacement (Chevy & GMC)
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- Опубликовано: 27 июл 2024
- In this video we will be replacing a power brake vacuum booster which has developed a very loud and noticeable vacuum leak on an old body style (OBS) GM truck. Such a leak is easily identified from the "hissing" air sound made during prolonged brake pedal activation, as well as from the random tachometer RPM flutter that will occur from the vacuum leak effect on the engine itself. While it is "normal" to hear a short and slight hiss whenever depressing the brake pedal initially on these OBS GMT400 trucks, this should not be loud and persist while stopped with the pedal fully depressed (though some remanufactured units lack a quality foam silencer so are not as quiet as original GM boosters were).
The truck illustrated is a 1998 Chevrolet Cheyenne K2500, but the procedure and replacement part will be the same for any 1997 thru 2000 OBS truck with a vacuum power brake booster option (RPOs JB5, JB6, JB7). Chevrolet, GMC, and Holden for Cheyenne, Silverado, Tahoe, Yukon, Suburban, Sierra, and W/T trucks across C1500, K1500, C2500, and K2500 ratings. Fitment for model year 2000 is limited to Cadillac Escalade, and Chevrolet Tahoe Limited/Z71.
NOTE: Some remanufacturers of vacuum brake boosters do not replace all of the vacuum seals, so you can get a remanufactured booster that has a slight hiss out of the box as well. In these situations you just have to return the reman unit, and hope for a better rebuild in the replacement booster you get next. Such is the world of non-OEM aftermarket parts for these OBS trucks.
The eBay and Amazon search links below are paid links, for which I may be compensated and earn a commission, if you choose to buy the parts and tools shown in this video thru them:
Cardone 54-71085 remanufactured power brake vacuum booster (unloaded): ebay.us/gxk8eg or amzn.to/3uLzdgj (note: rebate link below Amazon price is for core return)
Cardone 5C-471085 brand new aftermarket power brake vacuum booster (unloaded): ebay.us/U5RIFW or amzn.to/3AqMuOP
Cardone 10-5000MCB brake fluid syringe: ebay.us/cfWV8a or amzn.to/3nAIHqv
LMC Truck 31-2305 power brake booster firewall gasket: www.lmctruck.com/1988-98-chev...
GM 15705042 brake pedal arm stud vacuum booster pushrod retaining clip: ebay.us/TzHkOl
GM 01470030 clamp for power brake vacuum hose to check valve: ebay.us/wTCHfZ
GM 11609949 nut (15mm nylon locking) for securing brake booster to firewall and master cylinder to brake booster: ebay.us/lnw6hk
ACDelco 14PB4064 / GM 19286764 remanufactured power brake vacuum booster (DISCONTINUED) superseded GM 18047682 (RPO code JB5/JB6 production sticker "DA") and GM 18047678 (RPO code JB7 - production sticker "XF"): ebay.us/EpwRIG or amzn.to/3nAPwbA
GM 15960241 power brake booster firewall gasket (DISCONTINUED): ebay.us/NkOtQt or amzn.to/3P3TMw8
GM C/K truck factory service manual: ebay.us/fRJN91
And if I've saved you some $$ here, consider some coins for the coffee tip-jar! ko-fi.com/drshock
1997 1998 1999 2000
Chapters:
0:00 - Problem overview
0:40 - Symptoms review
1:39 - Service manual procedure overview
3:40 - Preparing the master cylinder for removal
5:36 - Removing the master cylinder
8:18 - Disconnecting the brake booster vacuum line
9:51 - Locating the under dash fasteners
11:20 - Removing the brake booster pushrod retaining clip
16:52 - Removing the brake stoplight switch
17:37 - Removing four firewall retaining nuts
19:15 - Disconnecting the booster pushrod from the brake pedal stud
19:30 - Pushrod retaining clip inspection
20:08 - Tools used for under dash fastener removal
21:27 - Removing the brake vacuum booster from the vehicle
22:17 - Inspecting firewall gasket
22:36 - Brake booster replacement part identification
25:52 - Firewall booster gasket replacement information
26:57 - Installing the new vacuum brake booster
27:39 - Replacement retaining clip information
28:00 - Reconnecting the booster pushrod and stoplight switch
28:51 - Installing new retaining clip
30:40 - Reconnecting the vacuum hose to the booster
31:26 - Reinstalling the brake master cylinder
#drshock #obstruck #obstrucks
Disclaimer: DrShock, the alias for the human content creator for this RUclips channel, is not responsible for any damages, injuries, losses, or liabilities associated with any repairs, upgrades, or maintenance performed on yours, or any other, vehicle whatsoever. No warranty, express or implied, is made as to the accuracy or completeness of any information provided within this channel. Viewing and using the “as-is" information of this channel is totally at your own risk. Always wear personal protection equipment and follow appropriate vehicle manufacturer service manual guidelines with original manufacturer parts only when performing any repairs, upgrades, or maintenance upon any vehicle. 
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Mr. Shock, I am 77 years old and still try to do my own repairs whenever possible. In all of my times watching repair videos I have never experienced anyone as thorough, detailed, meticulous, and experienced as you are and I just wanted to thank you for all of your excellent work. George in Kasilof, AK. 1:46
Who knew, I was looking for a clear vid that would show me how to replace my brake light switch, and all the others on RUclips don’t really show u how, but here after I struggled with it, I find a good video showing me clearly, but it’s on a brake booster replacement video
This is the best repair video I’ve ever found on RUclips! You’re the man, appreciate all the hard work 🤙🏾
i was finna comment about this is one best step by step visual video i ever seen but everyone beat me to it glad i found your channel
I am am able to do "some" repairs on my truck, I was afraid of this one. Watched this video, very thorough, and was able to replace my brake booster with ZERO issue.
Thank you so much for the great video.
best walkthrough on line many thanks.
Phenomenal video, honestly the best repair walkthrough ive ever seen. Excellent stuff. 5 stars. Amazing!
Just picked up the additional tools that I'll need, wish me luck!
I'm working on a 97 S10, do you know offhand if it's a comparable procedure? I don't see my exact model listed in the description
S/T trucks of the same era will be similar, but different parts and layout than the C/K trucks.
@@DrShock Just finished and it seems to have been a success! Thanks again!
man this was an amazing video. you really got up super close and showed every bit of the job in all it's detail. something pretty hard to come by with these kids of videos all the time. going to attempt this on my 95 G20 Van. Thanks a million for this.
Great video, very detailed. The hardest part of this task is that little clip
EXTREMELY EXCELLENT VISUAL & EXPLANATORY PRESENTATION !!! STELLAR JOB ! DONE LIKE YOU CARE !!! Right-on !!! BRAVO⭐️⭐️⭐️⭐️⭐️
Thank you very much brother for this RUclips video that you have made. I was able to do my own work on my 99 chevy Tahoe and the brakes work wonderfully all their information on this video is priceless thank you.
I appreciate this video so much, I luckily got that clip off in under 10 minutes
I just swapped mine on my 1996 single cab swb last weekend. Bought the ac deloc from autozone and after I installed it realized the one they sold me the studs for that mount the master cylinder was actually shorter than my original stock booster.
Mybstock booster studs measured right at 1 1/2" and the one they sold me was 1 1/8 " and was the same part number as the Cardon. Moral of my story is check the studs before you mount it. Even though the numbers and everything else matched, they still are rebuilding these in Mexico and you might not get the right part.
Wonderful video you made. Thank you for all the details in the darn clip...such a blessing
You explained everything so perfectly and your video was excellent thanks to you im back on the road again .THANKYOU SO VERY MUCH!
Very informative video! It really helps when we know what we're getting into before tackling a job like this. Knowing the part numbers and tools needed is a big help also. Thanks for you're hard work making this video, great job!
Good job 👍 liked the detail camera views of the brake light switch. Tips and tools used awesome 😎. Thanks for the video. 🙏
Great job you are so patient with doing and explaining the job in detail , impressed and thanks for sharing
Another great video to have for future use. Thanks for sharing!
Great job with the step by step 👏 thank you. I feel confident doing this.
You da man! Followed your instructions to a tee and everything went back together as expected. Thanks bro!
Love your video! Especially the clip removal on the brake pedal pin. It helped tremendously! Thank you so much.
Thank you for your video I watched several and yours is the most informative good job with your camera shots under the dash I know it must’ve been very difficult for you to achieve but because you have you made this job easier for me and I’m sure others that will attempt to do this thank you again.
Awesome video, loved it!! , you are an amazing mechanic! Super helpful and super professional thank you for your amazing videos!!
Awesome, incredibly detailed video.
Great job explaining! Thank you!
Fantastic video! Now just gotta do it myself lol
Great video thanks for the pre job it helps big time!
Thanks for Sharing Video, Tips & info 💯‼️💯‼️
❤ awesome camera views taking the time and effort to get those is much appreciated bye many, bravo and thank you
thank you for making this
love your content
Thanks bro this was alot of help👍
Great video
Thank you for this video. I am not looking forward to this job at all. Just watching it made me wore out. but your video with every step is very helpful.
great video
Excellente my friend very helpfull...
Great video 1000%
Thank you very much for that very clear and for the tools to used..
Now o like the way yhis guy explains and shows it i can understand good
I appreciate this video. I've replaced my brake light switch and it made me talk ugly. I wish I knew about the 11mm socket. That worked great. My booster don't hiss like that one. When you apply the my brakes, the booster hiss/whoosh 1 time. Thanks
Thanks, a one time initial hiss sound on braking can be normal for these GMT400 trucks - with the factory stock brake setup. When the vacuum seal goes inside the booster, you get what this video shows. This one here lasted about 25 years, so not bad at all.
Thanks for video helped me out alot I'm not a every day chevy truck machanic and looked under dash for 30sec and sead let's go watch a video
Just now got that clip off and it only took me 7 months!
The old booster is a bit bigger than the new one ...yh I know video is old I don't care it's great content still 😏
Great video. I’m going to be replacing my entire dash. Wondering if it would simplify the process if I replaced the booster with the dash out?
She clipped into plaztion😂😂😂😂I love it.
Great video. Thanks for the instructions!! I’ve got a 92 one c1500 and you mentioned the pushrod might be a different length. Any idea how long mine is? I didn’t find the list? Thanks again!
Unless you know you had the original GM assembly line one, just focus on comparing to the remanufactured parts. If what you had before was working, then you just want to be sure what you replace it with at least cosmetically matches.
Great vid. By the way Amazon carries that Cardone.
Thanks. Yep, there's an Amazon link in the video description, as well as eBay.
@@DrShock thankyou sir.
Great video, I just finished replacing my brake booster but now on my 99 Tahoe it doesn't want to crank, I can bypass the relay and get it to crank over and start, but it's locked in park and won't let me shift
Likely a problem with the brake switch when you had to remove to do this repair. It's a big square cream color plastic device sitting on top of the push rod into the booster. Check the position/orientation on that as you can't shift without that switch giving the correct signal to the powertrain module.
Every single website says the major sign of power brake booster is a stiff pedal? My pedal isn’t stiff but it makes this exact noise and my idle fluctuates in the same way
Same here
Great video! Question for you: I get the hissing noise as the brake pedal is returning to it's stationary position after I depress it. What would cause this?
Thanks. Can't say I've come across one behaving that way, but I would imagine it's just an atypical variation of the same vacuum seal leakage inside the booster. To eliminate a mechanical/resistive source, operate the pedal with the engine off, once the vacuum is exhausted in the booster there should be no hissing. If you still notice it, it's more likely the mechanical mechanism slightly rubbing inside the booster instead.
@@DrShock thank you sir!
Did not show any parts of dash removed but very good video. Thanks
There's no part of the dash you should be removing for this job as everything is accessible from underneath, so there's nothing to show removed there. ;-)
Thank you for that very helpful video! following this video I have run into an issue! I was hoping you could help me with this. I just installed a brand new brake booster but now in addition to the hard pedal like the old brake booster was apparently causing I now have this new issue of suction noise is it possible it is installed wrong? how could that be possible?
Thanks. Unlikely it could have been installed _wrong_ on the model year trucks that this video covers. The only vacuum attachment point is at the check valve, on the underhood side. And then at the vacuum hose coming from the intake manifold. If there's any air sound in the interior of the truck, this points to an internal seal failure of the vacuum booster. If the sound is heard outside, under the hood, double check that the check valve is fully seated and the vacuum hose is fully connected and secured.
Great video. My husband and I just replaced the booster, Master cylinder, and bled the brakes;
and the symptoms are the same. Our only conclusion is that the remanufactured booster is bad. We checked the vacuum from the engine, and it was ok. Any ideas?
If you are getting the same _continuous_ vacuum leakage sound past the seal as I showed in the vid, from inside the cab, then yeah that would tend to indicate a defectively remanufactured brake booster.
Hey there I was curious to know if you could help me with my 2001 s10, this is the issue.
*I have converted the truck to all Brake calipers*
Brake pedal pressure is completely lost when the engine is at an idle.
I have installed the same Brake Booster, and an orielly brand master cylinder.
The main difference that I have seen between what I have done and your video is that gasket. >between the firewall and the Brake booster<
Does that sound like the culprit ? [We didn't have any local store that carried that gasket. ]
I have ordered a jegs disc/disc master cylinder and a GM disc /disc proportion valve.
This is to ensure the entire system has controlled variables.
Please let me know if you have any ideas.
(I'm a welder from cleveland Ohio, this is my winter truck)
Excellent video. Is it very different for a manual transmission? or about the same.
Thanks. I wouldn't expect any difference for a manual other than the additional obstruction of the clutch pedal under the dash area where you are working for this job.
@@DrShock thank you so much for answering. I'll definitely give it a try.
man i hope mine is this problem
brakes are nice and hard until i turn the pickup on and it goes woosh and to the floor.
So i have a question. Buddy whos borrowing my 97 suburban while im deployed told me that the brakes would push back and hiss and as well as stall when the brakes finally did contact. Would you say in your opinion this is whats causing the problem?
Maybe. Tough to say without seeing the truck. A short quick hiss is possibly normal for these years if it's just on initial apply. But if continuous, the sound would have to be coming from the vacuum booster. Stalling _might_ be related to the booster, due to a vacuum leak affecting the engine RPM. But stalling while braking can also have several other root causes.
Actually, a question: I've replaced the booster and master cylinder, replaced the front brake hoses, bled the whole brake system twice, and I find that the brake pedal feels a bit soft. The hissing that happened before is gone, and the brakes work fine even when I'm towing a load, but it just feels like the pedal is too easy to depress. It doesn't seem to get stiffer if I press the pedal multiple times, which makes me think it's not air in the system. Any thoughts?
It's hard to say for sure without a test drive of the truck. But it is a typical complaint with GMT400 era trucks running stock brake equipment, that they just have a soft pedal by design. Some things to make sure of for safety though, if you have ABS be sure it's bled with a scan tool as regular bleeding procedures will not remove air in the brake pressure modulator valve (BPMV) portion of the ABS controller. And be sure you check your rear drum equipment too, the pedal feel isn't limited to just the front operation/feedback.
But usually, I find these kinds of complaints for these particular model years to be _working as designed_ by GM. ;-)
@@DrShock thanks very much for your reply! I guess it must just be soft by design, as you said. I think I was running it with a dying brake booster for so long I forgot what the regular brakes felt like (don't drive this truck that often, it's just used for a bit of hauling every few weeks).
What is the part # of the other end of the vacuum line that plugs into the intake. Mine doesn't plug in tight in the intake.
For this particular engine, Vortec 5.7L V8, you can find it in the description of this video - ruclips.net/video/dsg8ZC-dFBo/видео.html
So i just replaced my master cylinder and brake booster as i was having issues (and still am with really soft brake pedal) With the new brake booster when i push on the pedal i hear air come out from the inside of the vehicle. But it doesnt keep making the noise like yours does in this video. If i hold the pedal down the noise stops but if i push it further down it makes an air noise until i stop pushing and hold. Is that normal? This 98 k1500 is really giving me a brain workout trying to figure out whats going on. Everything ive found to try has yet to work and im not sure what to do.
Depending on the quality of the rebuild, or aftermarket replacement if new, there can be _some_ actuation noise that may be mistaken for a vacuum leak. It's not unusual for there to be a very short _hiss_ kind of sound on initial application of the pedal using such parts that may be mistaken for a vacuum leak. It's not air escaping, but rather a sound coming from inside the booster mechanism itself. There should _not_ however be *any* extended sound of air flow under vacuum (like we showed in this video), or a negative effect on engine RPM visible on the tachometer (which would indicate a vacuum leak as well).
Personally, I don't believe it to be possible to get a _firm_ pedal on these old trucks anymore, as the original genuine GM brake system parts are no longer available and the aftermarket options are just not as good. It's not a safety characteristic in terms of the pedal feel and feedback, but rather totally cosmetic imo.
@@DrShock Thank you thats what i was thinking as well. Going to bleed everything again tomorrow with a vacuum bleeder to see if there is anymore air bubbles in the lines and try and adjust the rear drum shoes again to see if i can get them a tighter fit and then take it on a test drive. Really hoping my stopping distance will improve after messing with everything for the last 3 weeks.
Thats been my biggest concern and why i delved into all this in the first place. My stopping distance seems way to long and before i had to push the brake pedal all the way to the floor before i noticed and significant braking. (if someone stopped infront of me id be worried id rear-end them) Hoping to see some improvements from that.
Was the hissing sound when you pressed the brake pedal
Notice a hissing or wishing sound coming from under my dash by my feet 98 Yukon 5.7 vorteck
Would a bad brake booster cause the engine to stall when I put it on gear?
On the truck years this video covers, possibly as a vacuum leak can cause a stall, though this wouldn't be my first suspect. Easy test in the driveway/garage to eliminate this possibility though.
Keeping the transmission in park (and do not drive the truck with the vacuum hose disconnected as you'll have no power braking), disconnect the vacuum hose at the booster check valve (under the hood), and plug it off to prevent _any_ vacuum leakage. If the problem goes away when shifting out of park (again, don't drive it with the booster hose disconnected), then it was the booster. If not, you're one less component down the list of possibilities. ;-)
My 2009 chevy tahoe still makes the hissing sound when I brake, my mechanic said he bled them and that it's still going to make that noise. Is he right?
These trucks are at least a quarter of a century old now, most quite older. There's no longer OEM brake parts available for them, and the aftermarket parts are just not as good as genuine OEM. So yeah, you may have a *short* _hiss_ kind of sound on pedal actuation from time to time from the internal mechanism of the rebuilt booster (or aftermarket design if new).
You should _never_ have a continuous sound of air like was showed in this video though. That kind of continuous sound is *NOT* normal, but rather a vacuum leak due to an internal seal failure inside the power brake vacuum booster itself. You can also detect these vacuum leaks by observing the negative RPM impact to the engine on the tachometer.
Mine is doing it without hitting the brake. Then when i press the brakes it stops. Same thing? TIA!
Would it be recommended to bleed the brakes??
For this job, only if you disconnected the master cylinder brake lines. I believe for this video I mentioned the master was being replaced also (and covered in a separate video) but that's not always going to be the case.
Do I gotta replace the clip for the brake pedal
Yep, safety feature
my 2000 chevy silverado has a hissing noise after pressing on break pedal and has a abs and parking break light my friend said it might have a bad break booster anyone have any idea what may be wrong?
Either that or the abs control module depends on what it's all doing.
My truck won’t shift after doing this any idea why?
This is possibly because of the shift interlock solenoid. Check the brake switch and insure you have it mounted correctly.
You might also have an issue with the pushrod going into an aftermarket type master cylinder not having the stock length of travel. You can test for that problem by simply _unclipping_ the brake switch plastic from gripping the pushrod and see if it works now just dangling _upwards_ there (of course leave the switch electrically connected and with the metal safety retaining clip still attached).
Does that odometer say 385, same motor?
Original engine and transmission yeah.
Hello and best regards from Hungary, very great and informative video! I have a first generation fiat bravo , manufactured in 1997. It has no ABS. All mechanical brake parts are new on the front and back also, but on the MOT they tested the brake power and its only 50%...So of course mot is failed. They said maybe the brake booster is the reason. One sympthom is indicate that is true: when the engine off and i push the brake pedal lot of times, no change in the pedal hardness feeling. I mean it is not sinking, not feels like spongy , it is standard hard, however not coming higher level like at my other car. But the strange is, When i start the engine and pressed the pedal , it is went down slightly a little bit like normaly should be. However i can hear a little shh shh noise when i press the pedal. Not noisy, it is similar like in my other car what is function very good. What do you think, this sympthom means my brake booster is over?
is that a bi-fuel book
No, just the regular service manual. There's a search link in the video description.
Wer he says get that guy out we in the south most time we will say get her out of there
Problem I’m having is when I press the pedal in it sticks and don’t come back up unless you wait or give it gas . I do hear a hissing sound when the engine gets shut off
Mine is hissing when I press the brake pedal
My Chevy 2009 whistles when I let go of the brakes .why is that ?
Don’t fight that clamp. Just pull the fitting out of the booster.