Air leaking out of MC causing brakelight to come on - The 1947 - Present Chevrolet & GMC Truck Message Board Network

oldblue1968chevy · 05-01-2010, 08:23 PM

I have air comming out of the hole (all the way thru MC). I can cover it wiht my fingers to seal it up. It used to not come out of this hole. It causes my brakelight to come on, and brakes to be really hard to push down. What do I do to fix it and why is it doing it? Thanks!

**Boog** · 05-01-2010, 08:26 PM

Your brake booster has gone bad. Replacement is necessary.

oldblue1968chevy · 05-01-2010, 08:36 PM

Really?!

crap, oh well it IS 40 years old

mclairmo · 05-02-2010, 05:24 AM

Bad booster, Autozone has replacements for about $100.

cdowns · 05-02-2010, 09:09 AM

a leak is a bad booster but i think theres additional problem with master cylinder causing the light to go on // i'd change both and while at it go over the whole brake system to tune it up to specs// the factory service manual has excellent info on the proper procedure to bleed the brakes for proper operation

powerdriver 1958 · 05-02-2010, 11:38 AM

There is a rubber seal that fits over the rod that pushes the master cly.and and fills the recess in the booster,Is that missing? Noticed fresh paint on the booster and i'm wondering if its pinched or fell out?

If you go the rebuilt/new booster don't be surprised if the master cylinder comes with it .Some re-builders won't sell one with out the other

oldblue1968chevy · 05-02-2010, 09:45 PM

its a new MC, i just put new paint on the booster to make it look better.. I'll check it out tomorow after school...whats this seal look like.

I pretty much dont have power brakes on the truck, theres a little but they dont help much

oldblue1968chevy · 05-02-2010, 10:23 PM

so I need a new booster?

should I go with the gold finish or painted one?......

oldblue1968chevy · 05-04-2010, 10:32 PM

Can I rebuild it? Dad was thinking I could rebuild it for cheaper, if you can get parts even..

05-01-2010, 08:23 PM	#1
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Air leaking out of MC causing brakelight to come on I have air comming out of the hole (all the way thru MC). I can cover it wiht my fingers to seal it up. It used to not come out of this hole. It causes my brakelight to come on, and brakes to be really hard to push down. What do I do to fix it and why is it doing it? Thanks! Attached Images __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

05-01-2010, 08:26 PM	#2
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,452	Re: Air leaking out of MC causing brakelight to come on Your brake booster has gone bad. Replacement is necessary. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

05-01-2010, 08:36 PM	#3
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Air leaking out of MC causing brakelight to come on Really?! crap, oh well it IS 40 years old __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

05-02-2010, 05:24 AM	#4
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Air leaking out of MC causing brakelight to come on Bad booster, Autozone has replacements for about $100.

05-02-2010, 09:09 AM	#5
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Air leaking out of MC causing brakelight to come on a leak is a bad booster but i think theres additional problem with master cylinder causing the light to go on // i'd change both and while at it go over the whole brake system to tune it up to specs// the factory service manual has excellent info on the proper procedure to bleed the brakes for proper operation __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

05-02-2010, 11:38 AM	#6
powerdriver 1958 Kid's Mechanic Join Date: Nov 2006 Location: Kansas City Posts: 8,241	Re: Air leaking out of MC causing brakelight to come on There is a rubber seal that fits over the rod that pushes the master cly.and and fills the recess in the booster,Is that missing? Noticed fresh paint on the booster and i'm wondering if its pinched or fell out? If you go the rebuilt/new booster don't be surprised if the master cylinder comes with it .Some re-builders won't sell one with out the other Last edited by powerdriver 1958; 05-02-2010 at 11:41 AM.

05-02-2010, 09:45 PM	#7
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Air leaking out of MC causing brakelight to come on its a new MC, i just put new paint on the booster to make it look better.. I'll check it out tomorow after school...whats this seal look like. I pretty much dont have power brakes on the truck, theres a little but they dont help much __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

05-02-2010, 10:23 PM	#8
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Air leaking out of MC causing brakelight to come on so I need a new booster? should I go with the gold finish or painted one?...... __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

05-04-2010, 10:32 PM	#9
oldblue1968chevy Grandpa in the rustmobile... Join Date: Nov 2008 Location: Spokane WA/Viola TN Posts: 11,422	Re: Air leaking out of MC causing brakelight to come on Can I rebuild it? Dad was thinking I could rebuild it for cheaper, if you can get parts even.. __________________ John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4

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