The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 01-19-2008, 02:04 AM   #1
truckguy_69
Registered User
 
truckguy_69's Avatar
 
Join Date: Apr 2007
Location: washington
Posts: 95
Brake Problem

well ive been having good brake presure for about a week after i replaced the master cylinder lid gasket and now it has no pressure till its all the way to the floor and the brake light comes on. i checked the fluid and its full to the top and the back one on the gasket is sucked up in to the lid. i poped it back to where it needs to be and had pressure for one braking and it did it again!

Last edited by truckguy_69; 01-19-2008 at 02:06 AM.
truckguy_69 is offline   Reply With Quote
Old 01-19-2008, 02:45 AM   #2
70rs/ss
Registered User
 
70rs/ss's Avatar
 
Join Date: Dec 2004
Location: Northern AZ
Posts: 7,270
Re: Brake Problem

The lid gasket is to keep the fluid in and air out, if the new gasket helped brake pressure you have a bad master cylinder and the gasket band-aided it for a little while. Try a new master cylinder, or at the very least bleed the brakes staring at the pass rear, then drv rear, then pass frt, then drvs frt. if still no pressure then get a master cylinder.
70rs/ss is offline   Reply With Quote
Old 01-19-2008, 02:57 AM   #3
Longhorn Man
its all about the +6 inches
 
Longhorn Man's Avatar
 
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
Re: Brake Problem

the light coming on in the inst panel indicates an imballance in the system.
You need to inspect for leaks from front to back, look at lines, connections, front and rear brake cylinders.
Look for fluid on the inside of the tires to indicate fluid leakage from the front and rear cylinders.
If no leaks are found, then bleed brakes and inspect again. Air got in the system from somewhere.

Last edited by Longhorn Man; 01-19-2008 at 02:58 AM.
Longhorn Man is offline   Reply With Quote
Old 01-19-2008, 07:24 AM   #4
truckguy_69
Registered User
 
truckguy_69's Avatar
 
Join Date: Apr 2007
Location: washington
Posts: 95
Re: Brake Problem

well i had just got the brakes bleed a week ago and the lid gasket 3 weeks ago and im not losing any fluid and the gasket keeps getting sucked into the lid, could the lid be bad?

Last edited by truckguy_69; 01-19-2008 at 07:24 AM.
truckguy_69 is offline   Reply With Quote
Old 01-19-2008, 07:39 AM   #5
Sweet72
Registered User
 
Sweet72's Avatar
 
Join Date: Nov 2003
Location: Alexandria, VA
Posts: 1,534
Re: Brake Problem

sounds like it wasn't bled completely, if bleeding won't fix it the MC may be defective as was suggested already. Why did I even bother to post?
__________________
'72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.
Sweet72 is offline   Reply With Quote
Old 01-19-2008, 07:41 AM   #6
Old Chevy Mech
Keepin it runnin!
 
Old Chevy Mech's Avatar
 
Join Date: Oct 2007
Location: Deep River, CT
Posts: 1,036
Re: Brake Problem

Have someone lightly press the pedal with the lid off (so as not to splash the fluid) and if you see any air bubbles coming up from inside the master cyl reservoir then the master cyl is bad as stated above. Its more prevelent when releasing the pedal.

Frank
__________________
1970 K-5 4X4 Blazer
1970 K-20 4X4 Long Bed

"Liberty Means Responsibility, that is why most men dread it"
Old Chevy Mech is offline   Reply With Quote
Old 01-19-2008, 08:18 AM   #7
68gmsee
Active Member
 
68gmsee's Avatar
 
Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
Re: Brake Problem

I'll chime in also. I agree with all of the above responses...

If all of the air is out and there are no leaks, then you have a mc that has gone bad. They're cheap.

Be aware that even a new or rebuilt master cylinder can go give you problems if not properly bled according to instructions or if you happend to get a defective one.
68gmsee is offline   Reply With Quote
Old 01-19-2008, 09:59 AM   #8
tim21391
Registered User
 
tim21391's Avatar
 
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
Re: Brake Problem

i bought a rebuilt master cylinder for 14 bucks at autozone....so far so good...my buddy of mine works there and he said they are good master cylinders too
tim21391 is offline   Reply With Quote
Reply

Bookmarks


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 Off

Forum Jump


All times are GMT -4. The time now is 02:16 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com