do i have a bad brake booster? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*1FaastC10* · 11-19-2003, 03:56 AM

i've noticed a few things with my 91 K1500 lately. the brakes seem to be grabbing evenly, and it doesnt pull either direction when they are applied. i am however experiencing a low pedal. today, i applied the brakes (while it was raining) and the pedal pulsated pretty violently as it went towards the floor. it stopped just fine, but made a hideous noise along with the pulsation. i've also noticed that if i step on the brake pedal before i start the engine i hear what appears to be some sort of a vac leak. if i dont step on the pedal before i start the engine its fine. anybody got any ideas what my problem may be? i'm all sorts of confuzzled here.

Tx Firefighter · 11-19-2003, 11:28 AM

Pulsating pedal is usually warper front rotors.

Hideous noise? Where is it coming from?

The deal with the pedal hissing before start up is normal.

SWEET7T · 11-19-2003, 01:45 PM

Quote:

Originally posted by 1FaastC10
...today, i applied the brakes (while it was raining) and the pedal pulsated pretty violently as it went towards the floor. it stopped just fine, but made a hideous noise along with the pulsation.

That sounds like the ABS was doing its job. The noise is from the system opening and closing really fast, to keep your tires from locking up and causes your pedal to pulsate. I olny say the ABS because you said it was raining, and of course causing the road to be more slick.
Under light braking, if you still feel pulsating or a wobble through your steering wheel, your rotors are warped and you need to get them 'turned'.

Quote:

i've also noticed that if i step on the brake pedal before i start the engine i hear what appears to be some sort of a vac leak. if i dont step on the pedal before i start the engine its fine. anybody got any ideas what my problem may be? i'm all sorts of confuzzled here.

That little sucking noise is normal. I can push really hard on the pedal in our vac brake trucks and they do the same thing.

loweredd · 11-19-2003, 03:29 PM

wouldnt a bad booster be super hard to push though, indicating a leak? (it would be like manual brakes, or worse?)

*1FaastC10* · 11-19-2003, 08:52 PM

i'm well aware of the ABS pulsation, and this was significantly more violent than that. the noise was more of a creaking noise than anything, and followed the pulsation of the pedal. it sounded as if it were coming from the pedal area, under the dash. i tried to recreate the circumstances in a parking lot, and it wouldnt do it again. my 82 did this to me one time too. just went away and didnt have any ill effects after that. on a note with the warped rotors, if that's what was causing this, i would feel it all the time. it only made the noise/vibration one time. everything else feels good except the low pedal.

SWEET7T · 11-20-2003, 02:08 AM

Try driving on the same part of road again..... Maybe it was rippled in one area and when you hit the brakes, your tires kinda skipped across the road. Just a thought

*1FaastC10* · 11-20-2003, 03:49 AM

i'll have to try that.

11-19-2003, 03:56 AM	#1
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	do i have a bad brake booster? i've noticed a few things with my 91 K1500 lately. the brakes seem to be grabbing evenly, and it doesnt pull either direction when they are applied. i am however experiencing a low pedal. today, i applied the brakes (while it was raining) and the pedal pulsated pretty violently as it went towards the floor. it stopped just fine, but made a hideous noise along with the pulsation. i've also noticed that if i step on the brake pedal before i start the engine i hear what appears to be some sort of a vac leak. if i dont step on the pedal before i start the engine its fine. anybody got any ideas what my problem may be? i'm all sorts of confuzzled here.

11-19-2003, 11:28 AM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Pulsating pedal is usually warper front rotors. Hideous noise? Where is it coming from? The deal with the pedal hissing before start up is normal. __________________ I'm on the Instagram- @Gearhead_Kevin

11-20-2003, 02:08 AM	#6
SWEET7T Try spinnin 4 rear tars Join Date: Sep 2003 Location: Salt Lake City, Utah Posts: 757	Try driving on the same part of road again..... Maybe it was rippled in one area and when you hit the brakes, your tires kinda skipped across the road. Just a thought __________________ SWEET7T 1970 C10, 2wd, LB, 307/TH350/3.08. PS, PB

11-19-2003, 03:29 PM	#4
loweredd www.loweredd.com Join Date: Aug 2002 Location: Struble IA Posts: 808	wouldnt a bad booster be super hard to push though, indicating a leak? (it would be like manual brakes, or worse?)

11-19-2003, 08:52 PM	#5
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	i'm well aware of the ABS pulsation, and this was significantly more violent than that. the noise was more of a creaking noise than anything, and followed the pulsation of the pedal. it sounded as if it were coming from the pedal area, under the dash. i tried to recreate the circumstances in a parking lot, and it wouldnt do it again. my 82 did this to me one time too. just went away and didnt have any ill effects after that. on a note with the warped rotors, if that's what was causing this, i would feel it all the time. it only made the noise/vibration one time. everything else feels good except the low pedal.

11-20-2003, 03:49 AM	#7
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	i'll have to try that.



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